A. Assumption Questions
B. Strengthen and Weaken Questions
C. Main Point Questions
D. Flaw Questions

IV-A. Assumption Questions (common question type)

An assumption is an unstated premise that supports the author's conclusion. It's the connection between the stated premises and the conclusion. The author's conclusion will depend upon the assumption being valid. Assumption questions are extremely common and have stems that look like these:

• Which of the following most accurately states a hidden assumption that the author must make in order to advance the argument above?
• Which of the following is an assumption that, if true, would support the conclusion in the passage above?
• Which of the following, if added to the passage, would make the conclusion logical?
• The validity of the argument depends on which of the following?
• Upon which of the following assumptions does the author rely?
• The argument presupposes which one of the following?

How to approach Assumption Questions

1.     Look for gaps between the premises and the conclusion. Go on an Assumption Hunt and spend a few seconds finding any holes in the argument.

2.     Ask yourself why the conclusion is true. Before you progress to the answer choices, try to get feel for what assumptions are necessary to fill the gaps between the premises and the conclusion.

3.     Take note of sweeping language or extreme statements.

Samples of an assumption question:

Question #1
When doing assumption questions, spend maybe 10 to 20 seconds trying to think of assumptions underlying the argument.

What ideas or words are in the conclusion but not stated in any premise or evidence? That's an assumption.

A study released by the American Dental Association shows that people who gargle with Berry Pop Soda are 20% less likely to get cavities. We should therefore stock up on Berry Pop Soda and prepare ourselves for increased demand.

Quick! What assumptions are in this argument? Think about it creatively and quickly. The premise is a new report coming out, and the conclusion is that it would lead to increased sales. That's quite a leap!

Let's quickly brainstorm some assumptions:

1.     The study was just released in medical journals and released to major media outlets so people know about it.

2.     Berry Pop soda is an attractive product. It may be good for teeth because it tastes like toothpaste!

3.     Berry Pop is not as effective as conventional mouthwashes at cavity prevention.

4.     Berry Pop has name recognition. Have you ever heard of Berry Pop?

Question #2

Apartment building owners argue that rent control should be abolished. Although they acknowledge that they would increase rents in the short term, owners argue that in the long term the rent increases would lead to greater profitability. Higher profits would lead to increased apartment construction. Increased apartment construction would then lead to a greater supply of residences and lower prices as the supply of apartments increases. Thus, abolishing rent control would ultimately reduce prices.

Express that complicated argument in your own words.

Premise 1: Abolishing rent control will increase the supply of housing (premise).

Premise 2: Greater supply leads to lower prices (premise).

Conclusion: Abolishing rent control leads to lower rents (conclusion). It is a supply/demand argument.

Try to find gaps between premises.

Look at premise 1: Abolishing rent control will increase the supply of housing.
This premise seems reasonable. Higher profits draw increased supply.

Look at premise 2: Greater supply leads to lower prices.
This is a supply/demand argument; greater supply leads to lower prices. However, there is something missing: supply and demand requires a discussion of demand. Indeed, demand is missing; that is the hidden assumption.

Sample Question

Since the late 1970s and early 1980s, tax regulations and other changes have encouraged increasing numbers of venture capitalists and entrepreneurs to start new enterprises. Since 1980, some one-half million new ventures have been started. Not all have succeeded, of course.
The above statement makes which of the following assumptions?

a.     Success in starting a new business depends in large part on sound financial planning.

b.     Social incentives motivate investors just as much as financial rewards.

c.     Financial incentives are associated with new business starts.

d.     Most new business ventures succeed initially but fail later on.

e.     Venture capitalists are motivated by non-monetary gains.

Explanation:

This is an "after this, therefore because of this" argument. It assumes that tax changes since the 1980's have increased the number of small businesses.

a.     may be correct, but there is nothing in the passage to substantiate it.

b.     is the second best answer. However, it cannot be inferred that social motives are just as strong as the financial motive, given that the passage states that tax regulations motivated increasing numbers of entrepreneurs to invest.

c.     is the correct answer.

d.     may be eliminated because of the word "most."

e.     there is no evidence in the passage to support this answer.

IV-B. Strengthen and Weaken Question (very common question type)

These are the most common critical reasoning questions, so read this chapter with great care. The whole trick on the Strengthen/Weaken question is to strengthen or weaken the assumptions. If an unstated assumption is the glue that holds an argument together, then weakening or strengthening it will weaken or strengthen the argument.

These Strengthen/Weaken questions don't ask you to change the conclusion or the premises, those are fixed; it is the unstated assumptions that are in flux.

Strengthening and Weakening is not the same thing as proving something true or false. Instead the right answer will support(strengthen) or cast doubt upon(weaken) the required assumptions, while also being relevant to the premises.

Here are some examples of Strengthen/Weaken question stems:

Strengthening:

• The conclusion would be more properly drawn if it were made clear that.
• Which of the following, if true, would most strengthen the conclusion drawn in the passage above?
• The argument as it is presented in the passage above would be most strengthened if which of the following were true?

Weakening: (note that when it says "if true", means that you must accept the validity of the statement)

• Which of the following, if true, most seriously weakens the conclusion drawn above?
• Which of the following, if true, would provide the strongest evidence against the above?
• Which of the following, if true, casts the most serious doubt on the conclusion drawn above?

Tips for Weakening Questions:

1.     Try to find one necessary assumption in the passage. This is what the right weakening answering may target.

2.     The All Things are Equal fallacy is very common on these questions, so keep your eyes out for it. When things are compared over time, the assumption is that background factors remain constant (when they might be changing). So, a good answer might be pointing out that some background factor did change. This would then invalidate their After this, therefore because of this argument because another factor may have caused the change.

3.     On Weakening questions where the question compares two things, often many confounding factors are ignored. When you see a Weakening question that compares two things or tries to show them as similar, look for an underlying confounding factor that makes such a comparison problematic.

4.     There will likely be two or more choices that weaken the argument. In this case, go up to the passage, re-read it carefully and see which one is more directly relevant to the premises and the conclusion and targets the assumption most effectively.

5.     Common trap answer choices include:

·         A statement that strengthens (and doesn't weaken) the assumptions and the overall argument- a trick opposite.

·         A statement with information not relevant to the argument.

·         A statement that requires additional facts to have value.

6.     The final answer that remains is the correct answer.

Sample Questions

1.     Fairfield’s postal service is badly managed. Thirty years ago first-class letter delivery cost only three cents. The price has increased sevenfold since then and the reliability and speed of service have declined as well.
All of the following would tend to weaken the conclusion of the argument above EXCEPT:

a.     The volume of mail handled by the postal service has increased dramatically over the last thirty years.

b.     Unprecedented increases in the cost of fuel for trucks and planes have put severe upward pressures on postal delivery costs.

c.     Private delivery services usually charge more than does the postal service for comparable delivery services.

d.     The average delivery time for a first-class letter three decades ago was slightly longer than it is today.

e.     The average level of consumer prices overall has increased fourfold over the last thirty years.  

Reviewing Answer Choices

a.     The volume of mail handled by the postal service has increased dramatically over the last thirty years.
This would seem to excuse the poor service/price because the postal service has had to overcome a massive increase in volume.

b.     Unprecedented increases in the cost of fuel for trucks and planes have put severe upward pressures on postal delivery costs.
This would seem to excuse the poor service/price because costs have increased dramatically.

c.     Private delivery services usually charge more than does the postal service for comparable delivery services.
This would seem to excuse the poor service/price because other services are not as efficient.

d.     The average delivery time for a first-class letter three decades ago was slightly longer than it is today.
This shows they have made improvements in service, suggesting that the postal service isn't all that bad after all.

e.     The average level of consumer prices overall has increased fourfold over the last thirty years.
Since the price of postage has increased seven times over, this suggests that postal prices have increased at a rate much quicker than inflation. Thus, choice E does support the original argument, making this the correct answer.

2.     In many pre-schools, children tend to get colds before their resistance develops, and the colds become much less frequent over time. It is clear that a child's immune system requires them to get several colds before it is fully activated and able to effectively deal with colds.
Which of the following, if true, most seriously weakens this theory?

a.     Children commonly spread viruses and bacteria in a small closed environment.

b.     The use of Vitamin C increases resistance to the common cold and decreases its frequency.

c.     Parents stock up on cold medicine after a child gets sick that alleviate the symptoms of a cold.

d.     There are many strains of the cold virus, and children develop resistance to individual strains.

e.     White blood cells fight infection and their production levels are stimulated by high infection levels.

3.     Reviewing Answer Choices

a.     Children commonly spread viruses and bacteria in a small closed environment.
Not Relevant

b.     The use of Vitamin C increases resistance to the common cold and decreases its frequency.
Not Relevant

c.     Parents stock up on cold medicine after a child gets sick that alleviate the symptoms of a cold.
This choice presents another possible reason to undermine the argument, but the medicine deals with symptoms, not the cold per se. So it is not reducing an instance of a cold, simply decreasing its symptoms (no more runny noses!).

d.     There are many strains of the cold virus, and children develop resistance to individual strains.
This choice suggests an alternative explanation for the apparent improvement in a child's ability to fight colds: the child simply becomes immune to individual viruses. So, the theory that a child's immune system needs to be “activated” isn't the case, it is an issue of exposure to certain strains. By suggesting a different causal process to explain the reduction in colds, this answer choice effectively weakens the argument.

e.     White blood cells fight infection and their production levels are stimulated by high infection levels.
The observation is decreased colds among children and the explanation is that constant exposure to colds “fully activates” an immune response. This choice supports the argument, but the question asks for what weakens it.

IV-C. Main Point Questions (inference)

While above we analyzed an argument's assumptions, here we analyze its conclusions.  In Main Point questions, the argument’s conclusion is usually not stated directly. To find the conclusion, first identify the premises and then think about what, if any, conclusion could be drawn from the premises. Main Point questions differ from the other critical reasoning questions in that the provided argument doesn't contain flaws – it’s simply missing a conclusion.

Here are some examples of Main Point question stems:

• The main point of the passage is that...
• Which of the following statements about... is best supported by the statements above?
• Which of the following best states the author's conclusion in the passage above?
• Which of the following conclusions can be most properly drawn from the data above?
• Which of the following is [implied, must be true, implicit, most reasonably drawn] in/from the passage above?
• Which of the following conclusions can most properly be drawn if the statements above are true?

How to approach Main Point Questions:

1.     Analyze scope: Main Point junk answers will typically be outside the scope of the passage. Be careful to examine the scope of the question: is it very broad, or very narrow, or somewhere in between? Main Point answers must be within the scope of the passage. Your opinions or information or irrelevant to the passage are always outside the scope.

2.     Don't jump into the Assumption Hunt. These questions usually don't contain glaring assumptions. Instead, these questions generally test your ability to derive a conclusion from stated premises.

3.     Knock out answers with extreme wording. Main Point answers typically do not use only, always, never, best or any strong words that leave little wiggle room. The right answers on Main Point questions will generally use more qualifiers and less extreme language.

4.     Try to fully understand what the passage's point is and the exact reasoning used in the argument so that if the question asks you to extend that reasoning, you will be are able to accurately do so.

5.     Use the process of elimination. Main Point questions typically have two or three good answers that are semi-plausible. The best way to tackle these questions is to gradually eliminate the possible answers until you have one or two and then choose the last one by scope.

Sample Questions

1.     Although Locke has been hailed as a giant figure in European intellectual history, his ideas were largely borrowed from his predecessors, who are now unfairly neglected by historians. Furthermore, Locke never wrote a truly great book; his most widely known works are muddy in style, awkwardly constructed, and often self-contradictory.
With which of the following would the author most likely agree?

a.     Locke made use of ideas without acknowledging his predecessors as the sources of those ideas.

b.     Current historians are re-evaluating Locke’s work in the light of present-day knowledge.

c.     Locke's contributions to the development of European thought have been greatly exaggerated.

d.     Historians should reexamine Locke's place in European intellectual history.

e.     Although Locke's ideas were important, his way of expressing them in writing was sadly inadequate.

Explanation: The author makes two assertions about Locke: that his ideas were not original, and that his books were not very good. On the basis of these assertions, the author concludes that Locke's reputation as an intellectual giant is undeserved. Choice (C) accurately summarizes this conclusion.

a. Locke made use of ideas without acknowledging his predecessors as the sources of those ideas.

Focuses on a subsidiary point, not the main idea; moreover, it makes an assumption unsupported by the passage: namely, that Locke did not acknowledge the sources of his ideas.

b. Current historians are re-evaluating Locke’s work in the light of present-day knowledge.

Is wrong because although the passage clearly indicates that the author is "re-evaluating" Locke's work, it does not suggest that "current historians" in general are doing so.

c. Locke's contributions to the development of European thought have been greatly exaggerated.

Similarly, (d) implies that the author recommends that other historians re-examine Locke. Since no recommendation exists in the argument, Choice (c) is the only option.

d. Historians should reexamine Locke's place in European intellectual history.

Is tricky because it is a good answer, but it is not the best answer. (C) best expresses the point, that Locke's contributions were not original.

e. Although Locke's ideas were important, his way of expressing them in writing was sadly inadequate.

This is not addressed in the passage.

2.     In 2005, Gotsland used three-times as much energy from non-renewable sources as from renewable sources. Gotsland's proposed ten-year energy plan would result in the country using as much renewable as non-renewable energy by 2015, while using a larger amount of energy than in 2005.
Which of the following must happen for Gotsland's plan to work?

a.     By 2015, Gotsland will more than triple its use of energy sources.

b.     Gotsland will have to make a political effort to have a more sustainable energy economy.

c.     By 2015, Gotsland will have to decrease its reliance of non-renewable energy sources.

d.     By 2015, Gotsland will more than triple its use of renewable energy sources over 2005 levels.

e.     New technologies must be developed to make the cost of renewable resources more competitive with renewables.

Explanation: In questions like these, where they start throwing around numbers and you scratch your head, thinking… "didn't I already do the quant section?", it might help to do Plugging In.

In a quant math problem we would translate words to numbers, so let's do that here. In 2005, Gotsland used three-times as much energy from non-renewable sources as renewable sources. Well, we can substitute 50 megawatts of renewable energy and 150 megawatts of non-renewable for what we have in 2005 (total of 200 megawatts).

Let’s look at the next statement: Gotsland's proposed ten-year energy plan would result in the country using as much renewable as non-renewable energy by 2015, while using a larger amount of energy than in 2005. Well, this means that in 2015 they will be using more than 200 megawatts AND renewables will be at least 150 (the number we’ve assigned to current non-renewables). So it needs to triple its use of renewables.

Now that we have our facts laid out we can review the answer choices.

a. By 2015, Gotsland will more than triple its use of energy sources.

                       Gotsland does not need to triple its energy sources (just renewables).

b. Gotsland will have to make a political effort to have a more sustainable energy economyIsn't relevant.

c. By 2015, Gotsland will have to decrease its reliance of non-renewable energy sources.

Gotsland doesn't need to decrease its use of non-renewables. It is mathematically possible for it to increase the total usage of total energy. In this scenario, non-renewables remains at 150 and renewables increases to 150 as well.

d. By 2015, Gotsland will more than triple its use of renewable energy sources over 2005 levels.

Yes, Gotsland MUST at least triple its use of non-renewables (to be at least 150 megawatts). This is the best answer.

e. New technologies must be developed to make the cost of renewable resources more competitive with renewables.

This may be the case, but there is nothing in the question to make this point.  

IV-D. Flaw Questions (uncommon)

These questions ask you to recognize what's wrong with an argument. Most of these questions require you to point out a fallacy in the argument. These should be easy for anyone who has prepared with 800score because of our extensive section above covering the most common logical flaws.

Here are some examples of typical flaw question stems:

• Which one of the following contains a flaw that most closely parallels the flaw contained in the passage?
• Which one of the following best identifies the flaw in the above argument?
• In presenting her position, the author does which one of the following?

Example 1:
John: We should oppose any attempt to register firearms. Such regulation is the first step to confiscation of all weapons and the elimination of our constitutional right to bear arms.

Ted: This is preposterous. Many things in society are registered, such as cars, babies, boats and lanes, yet these items have never been confiscated.

What are the flaws in the reasoning above?

Analysis:
Ted is making a faulty analogy between registration of guns and registration of cars and babies. But, guns are frequently used as instruments of intentional violence and therefore may be more likely targets for confiscation.

John is making a slippery slope argument that registration of firearms must invariably lead to the elimination of a constitutional right.

Example 2:
John: I don't want to die in an accident. Every few days on the TV news I hear of a major plane crash somewhere in the world. I would never fly planes; they are too dangerous.

Ted: Nonsense, statistics show that airplanes are the safest mode of transportation on a per-mile basis.

John: The answer, then, is not to travel such long distances.

Analysis:
John is pointing out that plane crashes are always in the news, and concludes that they must be very dangerous. The TV news, however, is a biased sample of all accidents. Minor traffic fatalities around the world rarely make the news, but are far more common than plane crashes. 

Ted points out the obvious: that on a per-mile basis, planes are safer, yet planes can travel ten thousand miles, so a long trip does entail risk. So ultimately John's analysis is to play it safe: don't travel long distances at all.

A. Executive Decision Making
B. Paradox - Research Conflict Questions
C. Deductive Reasoning
D. Style of Reasoning Questions

V-A. Executive Decision Making

When reading these stems, pretend you are the CEO of a Fortune 500 company and the GMAT question is a salesman or a manager with a proposal: "Given the advertising costs….. should the new marketing campaign... ?”.

These questions ask you to come up with the most effective, efficient or appropriate way to solve real world problems such as the following:

• Helping a business improve its profitability
• Dealing with a public health issue
• Improving performance among workers or students
• Fixing a sociological problem
• Cost-benefit analysis.

The stems will look like this:

• Which of the following strategies is most likely to prevent the decline in...
• Which of the following proposals would be most effective in...

Examples of Cost-Benefit Analysis:

Cost-benefit analysis is a technique used to aid decision-making.  By translating all possible costs and benefits into monetary terms, cost-benefit analysis makes it possible to weigh the costs and benefits of pursuing any course of action. It is often used in making business decisions, and may appear in the Analytical Writing Test in addition to Critical Reasoning questions.   Examples of cost-benefit analysis:

1.     Revenues - costs = profits

If you want to boost profits, cut costs or increase revenues.

2.     Cost - Benefit Analysis

If you want to make a sound business decision, evaluate the costs against the potential benefits.

·         Is something worth the cost?

·         What are the benefits of a course of action and what are the costs?

·         In the global warming example above (Section III-C)...

§  What would be the benefit of lowering carbon dioxide emissions?

§  What would be the cost?

§  What is the probability of a worst-case scenario global warming situation taking place?

§  What would be the cost of this scenario?

§  Is cutting carbon dioxide the most effective way to fight global warming?

§  If we spend $1 trillion now, what is the interest cost to prevent something that happens 100 years from now? Obviously the cost would be many, many trillion.

V-B. Paradox Explanation Questions

A paradox is a statement or proposition that seems self-contradictory or absurd but in reality expresses a possible truth.

These questions present you with a paradox and ask you to resolve it or explain how that contradiction could exist. Paradox questions are rare and more common at the higher skill levels. These questions usually contain the keywords explanation, resolve or account.

These questions often ask you to play the role of a top researcher where you have to reconcile conflicting data.

Here are some examples of the ways in which these questions are worded:

• Which of the following, if true, would help to resolve the apparent paradox presented above?
• Which of the following, if true, contributes most to an explanation of the apparent discrepancy described above?
• Each of the following could help account for this discrepancy, EXCEPT:

Sometimes paradox questions will have two speakers or portions of the text in bold. In these instances, they will ask you to compare the statements and resolve the conflict.

How to approach paradox questions:

1.     Read the argument and find the apparent paradox, discrepancy, or contradiction.

2.     State the apparent paradox, discrepancy, or contradiction in your own words.

3.     Use POE (process of elimination). The best answer will explain how both sides of the paradox, discrepancy, or contradiction can be true. Eliminate answers that are out of scope.

Examples
Inflation rose by 5.1% over the 2nd quarter, up from 4.1% during the first quarter of this year, and higher than the 3.3% recorded at the same time last year. However, the higher price index did not seem to alarm Wall Street, as stock prices remained steady.
Which of the following, if true, could explain Wall Street’s reaction?

a.     Stock prices were steady because of a fear that inflation would continue.

b.     The President announced that he was concerned about rising inflation.

c.     Economists warned that inflation would persist.

d.     Much of the quarterly increase in the price level was due to a summer drought's effect on food prices.

e.     Other unfavorable economic news had overshadowed the rise in inflation.

Explanation: This is a paradox because the high inflation report would seem to indicate that the stock market should go down.   Let’s look at the answer choices.  A fear that inflation would continue (choice a), an announcement by the president that he was concerned about inflation (choice b), economists' warnings about inflation (choice c), and other unfavorable economic news (choice e) would all tend to cause stock prices to decline and cause alarm on Wall Street.  Is that what we’re looking for?

No: what we are looking for instead is an explanation that suggests why a high-inflation report would not spook the markets.  Choice (d) is most appropriate for this. If most of the quarterly inflation was due to a rise in food prices caused by a drought, then other prices rose less (or no more) than in the last quarter. Since the drought is probably a temporary phenomenon, it may be expected that inflation will decline next quarter. Thus, there is no cause for alarm on Wall Street, and the high-inflation report should not scare the markets.

	The answer is in the answers If you don’t know anything about inflation, never fear – the GMAT questions will don’t require outside knowledge of very basic term.  They will provide clues – in this case, the “however” indicates that stock prices should not have remained steady.  If you’re stumped by the content of a passage, remember that everything you need to solve the question is provided in the question itself.

 

V-C. Deductive Reasoning (Must Be True, Missing Premise questions)

Deductive reasoning is the last topic we cover because they Deductive Reasoning questions are an entirely different species from every other Critical Reasoning question type. the rest of the GMAT critical reasoning questions and because In addition, they are quite rare.

Deductive vs. Inductive Reasoning

These Deductive Reasoning questions force you to follow highly specific logical rules. Most critical reasoning questions use soft and fuzzy inductive reasoning (with observations, lots of unstated assumptions, etc). Deductive reasoning is what a computer would do: cold hard logic following strict rules.  An easy way to identify Deductive Reasoning is to ask yourself: Does the conclusion follow directly from the premises?  If it does, that’s Deductive Reasoning. If it doesn’t (if it relies instead on unstated premises, or if the premises are presented as evidence, not proof, of the conclusion), it’s Inductive Reasoning.  You often use d Deductive reasoning is often used in the legal field, as well as in philosophical and mathematical proofs.  Here’s an example:

1.     You were on the neighbor's property.

2.     It is against trespassing laws to be on the neighbor's property.

3.     You are therefore guilty of trespassing.

Isaac Inductive says: I've noticed that every time I kick soccer ball up, it comes back down, so I guess this next time when I kick it up, it will come back down again.  (Reasoning from observation, Isaac Inductive is making an educated guess.)

Dennis Deductive says: You are merely applying Newton's law of gravity. Everything that goes up must come down. If you kick the ball up, it must come down.  (Reasoning from rules, Dennis Deductive is determining what must be the case.)

Types of Deductive Reasoning

Which of the following conclusions could only be answered reached by using pure deductive reasoning?:

1. Connecticut’s total population growth slowed last year.
2. Connecticut residents appreciate access to the ocean.
3. Connecticut’s legal residents are legal residents of the United States.
4. Connecticut has the highest per capita income of any state in the United States.

This is a bit of a trick question. Which of the conclusions above could only be reached via deductive reasoning?

1. It seems pretty obvious looking at population data that this conclusion relies on mathematical (and thus deductive) reasoning, but what about migrant workers, etc., who may not be documented? Because it says "total population", and not "documented population" or something of the like, we know that this conclusion probably relies on assumptions and observations instead of hard and fast rules, and so it is most likely an inductive conclusion.
   
   
2. This relies on popular opinion. Opinion is almost always inductive reasoning. (Think about it: are there any rules dictating what people like?)
   
   
3. In 1789, Connecticut became the first signatory to the U.S. constitution and all Connecticut legal residents became legal residents of the United States. This is pure deductive reasoning, as the conclusion is reached by just applying legal text rules. No evidence other than these rules need be presented in order for the conclusion to be reached.
   
   
4. Income statistics are assessed by gathering information, not by applying rules.  This is the result of observation, not pure logic, and is thus an inductive argument.

Remember, when assessing whether an argument is deductive, ask yourself: Does (or can) this conclusion follow directly from its premises?

Deductive Reasoning: 8 Rules to Remember

Because Deductive Reasoning is essentially reasoning from rules, Deductive Reasoning questions rely almost entirely on a set of logical rules.  This section presents 8 rules commonly used in GMAT Deductive Reasoning questions.  These rules of reasoning dictate what conclusions can be logically, validly reached based on what evidence.  Each rule is followed by examples of valid and invalid inferences derived from the rule.

Rule #1: If A, then B
If I press the power button, then the computer will turn off.

a.     Valid Inference: If not B, then not A
If the computer is not on, then I didn't press the power button.
(This logic rule is called the Contrapositive.)

b.     Invalid Inference: If B, then A
The computer is off, therefore I pressed the power button.
(There are other ways it could have shut off.)

c.     Invalid Inference: If not A, then not B
If I did not press the power button, then the computer is not off.
(The computer could have been turned off some other way, or never turned on. This logical error is called Denying the Antecedent.)

Example: Denying the Antecedent
If rains, then my grass is wet.
It isn't raining, then my grass must be dry.
(We could have a sprinkler system.)

Example using Rule #1

After spells of extreme cold weather in California or Florida, orange juice prices increase and orange juice shortages occur. Many supermarkets are reporting orange juice shortages. Therefore, there must have been a cold spell in Florida or California.
Which of the following is required for the validity of the argument above?

Argument structure:

Solution:

We need a fourth premise: (If C, then A):
If many supermarkets are reporting orange juice shortages, then there must have been a cold spell.
With this premise as an answer choice, we would be able to prove that the cold spell existed because of the reported shortage. The problem is that the Mr. GMAT is unlikely to be so kind as to provide If C, then A as an answer choice. That would be too easy.

So, how can we prove If C, then A? Apply Rule #1. If A, then B, has the logical inference If not A, then not B (this is called the contrapositive). The contrapositive of Rule #1 can stand in for the missing fourth premise, Rule #1 (If C, then A).  Basically, you are substituting the valid logical inference If not A, then not C for the logical rule If C, then A. They are logical equivalents.

Premise #4 should be in the form If not A, then not C: If there had not been a cold spell, there would not be an orange juice shortage. With this premise, you can now logically conclude that there must have been a cold spell in Florida or California, making the argument valid. 

Rule #2: If A, then B, If B, then C
If A, then B: If I press the power button, the computer will turn off.
If B, then C: If the computer is off, then the website will shut down.

a.     Valid Inference: If A, then C
If I press the power button, then the website will shut down.

b.     Valid Inference: If not C, then not A
If the website is not shut down, then I did not press the power button.

c.     Invalid Inference: If C, then A
If website is shut down, then I must have pressed the power button.
(There are other ways it could have been shut down.)

Rule #3: All A are B.
All GMATs are adaptive tests.

a.     Valid Inference: All non-B's are non-A's.
A test that is not adaptive is not a GMAT.

b.     Valid Inference: No non-B is an A.
No test that is not adaptive is a GMAT.

c.     Invalid Inference: No non-A's are B's.
No non-GMAT tests are adaptive.
(try the GRE)

d.     Invalid Inference: All B are A.
All adaptive tests are GMAT tests.
(try the GRE)

Rule #4: All A are B, All B are C.
All A are B: All GMATs are adaptive tests.
All B are C: All adaptive tests are computerized tests.

a.     Valid Inference: All A are C.
All GMAT tests are computerized.

b.     Valid Inference: No non-C is an A.
No non-computerized test is a GMAT.

c.     Invalid Inference: No non-A is a C.
No non-GMAT test is computerized.
(try the GRE)

d.     Invalid Inference: All C are A.
All computerized tests are GMAT tests.
(try the GRE)

Rule #5: Some A are B.
Some MBA programs are part-time programs.

a.     Valid Inference: Some B are A.
Some part-time programs are MBA programs.

b.     Invalid Inference: Some A are not B.
Some MBA programs are not part-time.

c.     Invalid Inference: Some B are not A.
Some part-time programs are not MBA programs.

Rule #6: Some A are B and Some B are C.
Some A are B: Some MBA programs are part-time programs.
Some B are C: Some part-time programs are poetry degrees.

a.     Valid Inference: Some B are A.
Some part-time programs are MBA programs.

b.     Valid Inference: Some C are B.
Some poetry degrees are part-time programs.

c.     Invalid Inference: Some A are C.
Some MBA programs are poetry degrees.

d.     Invalid Inference: Some C are A.
Some poetry degrees are MBA programs.

Why are C and D invalid? Although A and C share B, they don't necessarily share the part of B that links both of them individually to B.

Rule #7: Some A are B and All B are C.
Some A are B: Some MBA programs are accounting programs.
All B are C: All accounting programs are math intensive programs.

a.     Valid Inference: Some B are A.
Some accounting programs are MBA programs.

b.     Valid Inference: Some A are C.
Some MBA programs are math intensive programs.

c.     Valid Inference: Some C are A.
Some math intensive programs are MBA programs.

d.     Invalid Inference: All C are A.
All math intensive programs are MBA programs.

e.     Invalid Inference: All C are B.
All math intensive programs are accounting programs.

Rule #8: Either A or B, but not both.
Either a dog or a cat.

a.     Valid Inference: If A, then not B
If a dog, then not a cat.

b.     Valid Inference: If B, then not A
If a cat, then not a dog.

c.     Valid Inference: If not B, then A
If a not a cat, then a dog.

d.     Valid Inference: If not A, then B
If a not a dog, then a cat.

This rule has no invalid inferences because it’s black and white: if it’s not one, then it must be the other.  It can’t be both. 

Types of Deductive Reasoning Questions

There are two main types of Deductive Reasoning Questions: 

1. Must Be True

Make a deduction: extend the premises to make a direct logical conclusion. Example stems include:

• If the statements above are true, which of the following must also be true?
• Which of the following may be correctly inferred from the passage?
• Which of the following inferences is best supported by the statement made above?
  (Inference implies "must be true" on the test. In terms of vocabulary, Conclusion differs from Inference on the GMAT in that conclusions are the result of inductive arguments (using premises that may be unsupported or untrue), while inferences are the result of deductive arguments (using premises that must be true), and therefore must be true.)

2. Missing Premise

Find the missing premise: figure out which premise would be necessary to make the argument logically valid (necessarily true). Example stems include:

• The passage's conclusion is only true if which of the following statements is also true?
• Which of the following, if introduced into the argument as a premise, makes the argument logically correct?

How to Tackle Deductive Reasoning (Must Be True, Missing Premise) Questions):

1. Read the passage and look for the argument. Note that Deductive Reasoning questions may not be an in argument form.  Instead, Tthey may appear to be just be a series of facts. Nevertheless, try to find the argument, as these questions will depend on your being able to recognize the argument contained within the information presented, however it may be given to you.

2. Must Be True questions should always be tackled using POE (process of elimination). Go through every answer choice systematically and check if it is ALWAYS true. If you can find a situation where it is not true, eliminate it. Gradually eliminate answer choices until you have one left.

3. Missing Premise questions should be tackled used POE as well.  Go through every answer choice, and insert it into the argument.  Check if f the conclusion is ALWAYS (necessarily) true.  If you can find a hole in the argument, or if the conclusion isn’t necessarily true, eliminate the answer choice.  Eliminate choices until you find the one that makes the argument always (necessarily) true.

Example

Every store on Main Street in Summitville has an awning, and all of these awnings are either green or red.
If the statement above is true, which one of the following must also be true?

I. Some awnings in Summitville are green.
II If a store in Summitville does not have an awning, then it is not on Main Street.
III. If a store in Summitville has a red awning, then it is on Main Street.

a.     I only

b.     II only

c.     I and II only

d.     I and III only

e.     I, II, and III

Explanation: Note that this question is not an argument: it requires deductive reasoning.

Statement I may not be true: the question states that all of the awnings on Main Street are either green or red, but this does not preclude the possibility that all of the awnings on Main Street are red.

Statement III may not be true either: the question states that every store on Main Street has either a red awning or a green awning, but this does not preclude the possibility that a store on some other street has a red awning.

Statement II must be true: if every store on Main Street has an awning, then a store without an awning cannot be on Main Street. The correct answer is B.

 

V-D. Style of Reasoning Questions (uncommon)

Style of Reasoning questions ask you to describe how the argument was made, not necessarily what it says. These types of questions often ask you to analyze a passage using deductive reasoning. You will be asked to compare the style of deductive reasoning in two arguments or to choose the answer choice that uses the most similar deductive reasoning process.

Here are some examples of the ways in which these questions are worded:

• How does the author make his point?
• A's response has which of the following relationships to B's argument?

How to approach Style of Reasoning Questions

1. Read the argument and find the conclusion.

2. State the style of reasoning in your own words. Describe how the author gets from the premises to the conclusion, or how one person responds to another’s argument.  (For example: is the author providing examples to support his point, or is he trying to construct an airtight logical argument?  In questions with two speakers, does person A disagree with person B’s conclusion, or, alternatively, is person A arguing against one of person B’s premises?)

3. Use POE. The best answer will describe the reasoning used in the argument. Eliminate answer choices that don't match the reasoning used in the argument.

Examples

1.     There is a piece of folk wisdom expressed in the saying, "If it is not broken, don't fix it." A factory manager who accepted that saying would, on that account, be least likely to:

a.     agree to union demands, in the interest of safety, for better lighting in the stairwells and storage areas.

b.     respond to the difficulty of retaining skilled electronic technicians by establishing an on-site day-care center for small children.

c.     order the immediate replacement of windows broken in a strike.

d.     replace the quality control supervisor after receiving several complaints about defective units in recent shipments from the factory.

e.     institute a program of preventive maintenance for major pieces of production machinery.

Explanation: The point of the proverb "If it is not broken, don't fix it" is that tampering with something which is not an urgent problem is unnecessary. All of the alternatives involve the manager's making some change or taking some action. But the first four represent the manager's action as being a response to a particular existing problem. They are not against the spirit of the proverb. But preventive maintenance, over-hauling the machine before it breaks down, seems to be just what the proverb advises against. Choice (e) is the correct answer.

2.     Despite recent rumors of a new and improved building, employees should not expect renovations.
Without the support of the building's supervisor, the committee's plan usually fails. Two years ago, a plan to renovate the meeting rooms went under after the supervisor changed his mind and withdrew his support.

The bolded phrases play which of the following roles in the argument above?

a.     The first phrase offers advice and the second phrase states a conclusion.

b.     The first phrase states the conclusion and the second phrase supports that conclusion with an analogy.

c.     The first phrase states a conclusion and the second phrase provides evidence that weakens the conclusion.

d.     The first phrase states a position and the second phrase contains unrelated information.

e.     The first phrase states a premise on which the conclusion is based and the second phrase states the conclusion.

Explanation: This question asks you to identify the parts of an argument. The argument's structure is as follows: The expected outcome of a situation is presented; followed by a general rule for predicting the outcome of situations like these; followed by a specific instance of the general rule. The conclusion is in the beginning, while the argument in support of the conclusion follows after it.

Looking at the answer choices, we see that only two answer choices (b and c) put the conclusion first.

Choice (a)'s description of the first phrase as an offer of advice could be correct, but as the second phrase is not the conclusion, choice (a) is incorrect.

Choice (d) inaccurately describes the first phrase's function as stating a position.

Choice (e) describes the first phrase's function as a premise, which is incorrect.

Choices (b) and (c) are identical in their description of the first phrase as a conclusion, but differ in their descriptions of the second phrase. In choice (b), the second phrase should support the conclusion with an analogy. Is this accurate? Yes. The use of another, similar situation to illustrate the outcome of this situation constitutes an analogy, and one that supports the conclusion. Choice (c) suggests that the second phrase weakens the conclusion, which is does not. Choice (b) is the best answer.

Critical Reasoning Questions and Explanations

1.   Armchair anthropologists of the Victorian Era rarely visited the lands in whose cultures they proclaimed themselves experts, and were as likely as not to call the inhabitants “savages.”  By contrast, contemporary anthropologists, who are not taken seriously unless they have lived for a time among the people they study, are likely to use the more enlightened term “indigenous people.”

The author’s assertion about the superiority of contemporary anthropologists rests on which of the following assumptions about the word enlightened?

(A)       Victorian Era anthropologists often considered themselves enlightened even though they had never lived among the cultures they studied.
(B)       To be enlightened requires spending time among the people being studied.
(C)       The goal of contemporary anthropology is to become enlightened.
(D)       A person who has been enlightened can not, by definition, be called a savage.
(E)       Anthropologists must be enlightened before they are properly prepared to spend time among the people they study.            

Argument Construction

Situation: The passage contrasts Victorian Era anthropologists and contemporary anthropologists.  Contemporary anthropologists are considered more enlightened.

Reasoning: Which of the following identifies the assumption made in the use of the word enlightened?  The specific contrast drawn between the two groups of anthropologists is that contemporary anthropologists often spend time living among the people they study, whereas Victorian Era anthropologists usually did not.  According to the author of the passage, it is the time spent among the people they study that makes contemporary anthropologists more enlightened.

A         The passage does not discuss whether Victorian Era anthropologists considered themselves enlightened.
B          Correct. Contemporary anthropologists are considered more enlightened because, unlike Victorian Era anthropologists, they are likely to have lived among the people they study.
C          The passage does not make this claim.
D         The passage does not address the application of the word enlightened to people being studied.
E          The passage actually argues that anthropologists are enlightened because, or after, they spend time among the people they study.

The correct answer is B.

2.   Substances with similar scents often have vastly different molecular structures.  The scents of marzipan and cyanide, for example, both contain strong hints of almond.  The molecular structures of the substances, however, make them appropriate for nearly opposite uses: marzipan is often found in gourmet desserts, and cyanide is a powerful poison.

Which of the following conclusions can most reasonably be drawn from information in the passage above?

(A)       Molecular structures of substances with similar scents are always vastly different.
(B)       Molecular structures of unknown substances can often be predicted based on their scents.
(C)       Scents of unknown substances cannot be accurately predicted based only on their molecular structure.
(D)       Scents of poisonous substances are usually similar to scents of non-poisonous foods.
(E)       Marzipan and cyanide have similar scents, and can therefore be assumed to contain similar elements.

Argument Construction

Situation: Scents of substances often have no direct relationship to their molecular structure.

Reasoning: Which conclusion can be drawn from the passage? The main point of the passage is that the molecular structure of a substance does not determine its scent in a predictable way; substances of similar scents may have very different molecular structures, and vice versa. Marzipan and cyanide are examples of two substances that bear similar scents, but are so different in molecular structure that one is a food and the other is a poison.

A         The passage gives an example of two substances where this is the case, but does not argue that substances with similar scents are always different in molecular structure.
B          The passage argues the opposite.
C         Correct.  The passage uses the example of marzipan and cyanide to demonstrate that scents of substances cannot be accurately predicted based on their molecular structure.
D         Though this is true in the case of cyanide and marzipan, the word usually overstates the case made in the passage.
E          This conclusion cannot be drawn from the passage.

The correct answer is C.

3.   Studies have shown that men aged 18-27 who have owned a pet for at least 2 years before marrying are 35% less likely to divorce.  Researchers conclude that caring for a pet prepares men for long-term, healthy relationships in marriage.

Which of the following, if true, most strengthens the conclusion that men who have owned pets are prepared for healthy marriages?

(A)       Studies have shown that pet ownership drastically reduces daily stress levels.
(B)       Many successful marriages are based on emotional investment in a common interest, such as a pet.
(C)       Many men who have been married for 25 years or more continue to own pets.
(D)       Men who have not owned pets for at least two years before marrying are more likely to divorce.
(E)       Men whose wives who owned a pet for at least two years are equally as unlikely to divorce.

Argument Evaluation

Situation:  Researchers have concluded that men who have owned a pet for at least 2 years are prepared for healthy marriages.

Reasoning: Which option most strengthens the conclusion? Researchers base their conclusion on an assumed connection between sustained care for a pet and care for a spouse.  Men who care for pets, the argument runs, are also statistically more likely to sustain marriage relationships.  The correct answer will provide additional evidence of this correlation.

A         While this may be true, it does not introduce additional evidence to support the conclusion.
B          This option does not address the question of why men who own pets are less likely to divorce.
C          The question concerns men who have owned pets before marrying, not after.
D         Correct. This option provides additional evidence of a statistical correlation between pet ownership and the likelihood of divorce.
E          The question concerns men, not their wives.

The correct answer is D.

4.   The method by which attorneys at Watson & Crick bill for their time is inherently faulty. Accounting rules allow billing for a full hour even when an attorney has not worked on a specific file for a full 60 minutes.  Inevitably, this practice will lead to attorneys billing for more full hours than they actually work, passing on false expenses to clients anytime they open a file or pick up the phone.

Which of the following, if true, constitutes the best piece of evidence for countering the claim that attorneys at Watson & Crick are likely to bill for more full hours than they work?

(A)       Attorneys at Watson & Crick are required to attend annual ethics seminars, during which over-billing is strongly discouraged.
(B)       Senior partners at Watson & Crick typically bill over 60 hours per week.
(C)       Accounting rules at Watson & Crick only allow attorneys to bill for a full hour if they have performed more than one task for a client in a given day.
(D)       Attorney fees at Watson & Crick are calculated based on 15-minute segments of billing time.
(E)       Attorneys often have tremendous workloads and expect to be reasonably compensated for time spent working for clients.

 Argument Evaluation

Situation: The author of the passage claims that attorneys at a law firm are likely to bill for more hours than they work.

Reasoning: Which best counters the claim that attorneys are likely to bill for more hours than they work? The author of the passage is concerned with an accounting rule at the law firm that allows attorneys to bill for full hours even if they have not worked a full 60 minutes. It is assumed that attorneys will be able to bill for a full hour even if they perform only the briefest of tasks for a client.  If, however, it can be shown that the firm’s accounting rules will not permit the abuses that trouble the author of the passage, the claim will be effectively countered.

A         Though over-billing may be strongly discouraged, this option does not present conclusive evidence that abusive billing practices will be prevented.
B          The number of hours billed by attorneys at the firm provides no evidence for how many hours were worked, making a determination about over-billing impossible.
C          This option would actually strengthen the author’s claim that attorneys are likely to bill full hours for brief tasks.
D         Correct.  This option provides adequate evidence to counter the author’s claim.  If fees at the firm are determined in 15-minute, rather than an hourly, segments, then attorneys will not be able to bill for a full hour unless they have performed work during 4 15-minute intervals.
E          This may speak to the mindset of attorneys, but does not directly address the author’s concern.

The correct answer is D.

Don’t Mess With Nature is a coalition of the television industry, businesses involved in evening entertainment that depends on darkness — such as drive-in movie houses and outdoor live theaters — and farming. Its lobbyists have begun a campaign to persuade lawmakers to revoke daylight saving laws. Farmers argue that daylight saving is inconvenient to workers, who have to work late. The entertainment companies claim that daylight saving hurts their businesses, and thereby the national economy, to the tune of billions of dollars a year. Their lobbyists insist that, nowadays, daylight saving is of no discernible benefit to anyone. But environmentalists argue that it reduces the need for public and private lighting; health advocates maintain that it promotes outdoor exercise; and storeowners argue that the extra evening daylight encourages after-work shopping.

Which of the following, if true, would most support Don’t Mess With Nature’s argument?

A) The energy savings in summer resulting from a reduced need for artificial lighting are dwarfed by the energy demands of air conditioning, something that didn’t exist in 1917 when daylight saving laws were originally enacted.

B) Most people who exercise regularly prefer to use indoor facilities like gyms and racket-sports courts.

C) Three independent studies have shown that any reduction in in-store sales resulting from an end to daylight saving will be made up by an increase in online shopping during summer months.

D) As bio-fuels play an increasingly important role in the shift to renewable energy, the farming community is becoming the environmentalist’s best friend.

E) Doctors report that daylight savings time interferes with the natural sleep cycles of the population.

(C)  Don’t Mess With Nature is basing its argument for the repeal of daylight saving laws on the fiscal interests of the nation. It may not succeed — the arguments of environmentalists and/or health advocates may prevail — but the question asks us to find the answer choice that most supports Don’t Mess’s argument, and that is what we have to focus on.

Not only does choice (E) not directly address fiscal issues, it also doesn’t tell us anything about the health impact, so it is of dubious value to the debate. The question asks what adds to Don't Mess's argument, so you are looking for what will directly bolster their argument. Similarly, (B) has only very indirect relevance to financial aspects of the debate; even if one makes a connection between the nation’s physical health and its financial health, the health advocates are concerned about “fair-weather” exercisers who are motivated by the extra after-work daylight to walk, jog, play ball, etc. outdoors — not about committed exercisers who work out all year round indoors. (B) doesn’t negate their concern. <br>(D) might be true, but while daylight saving may be inconvenient to farmers, there is no suggestion that their production levels of bio-fuels are adversely affected by daylight saving, and therefore no evidence that the national interest is hurt by daylight saving. (A) is true, of course, but even if the saving in energy for lighting is less dramatic (as a proportion of total energy consumed) than it was in 1917, it is still whatever it is. So this fact does not help the Don’t Mess cause. <br>The fact that best supports the Don’t Mess cause is (C). On-street stores and shopping malls may suffer if daylight saving is discontinued, but the nation’s overall retail activity will not. That leaves the billions in extra business that will benefit the entertainment companies and, by extension, the nation, if daylight saving laws are repealed.

Questions 5-6 are based on the following

The life expectancy of people living below the poverty line in the United States is seven years shorter than the national average. A public health advocate argues that this is due to the fact that the poor cannot afford preventative medical care and often live in substandard housing where harmful substances such as lead paint and asbestos are common.  An expansion of health insurance services to those below the poverty line is an ultimately more cost-efficient way of raising life expectancy, because preventative care will forestall many expensive emergency treatments.

5.   Which of the following, if true, accurately identifies the most significant flaw in the public health advocate’s argument that health insurance services for those below the poverty line should be expanded?

(A)       The public health advocate does not provide sufficient information about the amount of money that will be saved by preventing emergency medical treatments.
(B)       The expansion of health insurance services to those below the poverty line will not address health problems caused by substandard housing.
(C)       Many health care providers are especially concerned with treating complications caused by exposure to lead paint and asbestos.
(D)       Census results do not clearly indicate what percentage of the population falls below the poverty line.
(E)       Lead paint and asbestos, though they cause medical problems, have not been conclusively proven to shorten life expectancy.

Argument Evaluation

Situation: A public health advocate argues that making more health insurance services available to people below the poverty line will save money by avoiding emergency medical treatments.  Emergency medical treatments are needed because those below the poverty line cannot pay for preventative medical care. Dangerous substances in substandard housing are mentioned as a second factor contributing to a lower-than-average life expectancy.

Reasoning:  What is the flaw in the advocate’s argument that health insurance services should be expanded? The public health advocate argues that expanded insurance services should be offered to those below the poverty line in order to prevent expensive emergency treatments.  The expansion of insurance services, however, would only address one of the factors the advocate claims contribute to a shorter life expectancy.

A         While this may be true, it is not the argument’s most serious flaw.
B          Correct. This option correctly identifies the flaw in the public health advocate’s argument. The advocate presents both lack of preventative care and substandard housing as factors shortening life expectancy, but the proposed solution only addresses one of the factors.
C          This option does not directly address the health care advocate’s argument.
D         The passage is concerned with matters relating to those below the poverty line, not with determining the exact percentage of the population it includes.
E          This option does not directly address the expansion of health insurance services to those below the poverty line.

The correct answer is B.

6.   The argument that an expansion of health insurance services to those below the poverty line will forestall expensive emergency treatments assumes that

(A)       Life expectancy can be increased by preventative medical care.
(B)       There are an adequate number of physicians available to provide preventative medical care to all those below the poverty line.
(C)       Expanded insurance plans will also treat complications caused by exposure to lead paint and asbestos in substandard housing.
(D)       Lead paint and asbestos are not as significant in reducing life expectancy as lack of preventative medical care.
(E)       Recipients of expanded health insurance coverage would take advantage of preventative medical care if they had the option. 

Argument Evaluation

Situation: A public health advocate argues that making more health insurance services available to people below the poverty line will ultimately save money by preventing emergency medical treatments.  The advocate says that emergency medical treatments are needed because those below the poverty line cannot pay for preventative medical care. Dangerous substances in substandard housing are mentioned as a second factor contributing to a lower-than-average life expectancy.

Reasoning:  Which is the assumption supporting the argument that health insurance will prevent emergency treatments? According to the advocate’s reasoning in the last sentence of the passage, more medical insurance translates directly into fewer emergency treatments.  The correct answer will most clearly undermine this direct connection.

A         While the passage as a whole assumes this, it is not the assumption made in connecting expanded health insurance with forestalling emergency treatments.
B          The number of physicians available is not directly relevant to the connection between health insurance and expensive emergency treatments.
C          Treatment of complications likely in substandard housing is not discussed in the passage.
D         This idea is not addressed in the passage.
E          Correct.  This option correctly identifies the assumption connecting expanded health insurance with preventing emergency medical treatments.  It is possible that those covered by health insurance would not seek preventative care.

The correct answer is E.

7.   Since viewers consistently imitate the behaviors they see on TV, continued exposure to violent programs will cause more people to consider violence an acceptable way of solving problems. In order to prevent a nationwide increase in violent crime, the government should ban the broadcast of violent programs.

Which of the following is most similar to the passage above in logical structure?

(A)       A judge finds the publisher of a chemistry textbook liable when a group of college students uses an experiment described in the book to start a fire in a rival’s dorm room.
(B)       A mother bans her teenage sons from watching violent television shows after they are involved in a series of fights with classmates.
(C)       A teacher hides the jar of candy she usually keeps on her desk in order to prevent students from gorging on it and ruining their lunch. 
(D)       A tour guide does not reveal to his clients the location of the town’s best ice cream shop because he has been upbraided by the shop’s owners for sending in too large a crowd.
(E)       A restaurant manager refuses to distribute fliers advertising an upcoming political rally because she does not support the candidate.

Argument Construction
                                      
Situation: The author argues that the government should ban violent television programs before the programs cause a national increase in violent crime. 

Reasoning: Which of the following uses a logical structure most similar to the logical structure of the passage? The author assumes in the first sentence that viewers who watch violent television programs will themselves become more violent. Since a higher crime rate is not desirable, the author suggests that the government deter more people from committing violent crimes by preventing the public’s exposure to the cause of crime: violent television programs. Also note that the passage proposes a solution designed to prevent, not to punish, violent crime.

A         The judge’s decision does not represent a preventative measure, nor does this example assume a continuing connection between exposure to chemistry textbooks and dorm fires.
B          Though this option contains a similar theme to the passage, the mother’s decision is made after the misbehavior of her sons and is intended as a punishment.
C         Correct. This situation is most similar to the passage in logical structure. The teacher assumes a connection between the observation of candy and students ruining their lunch by eating too much; her action is also a preventative measure.
D         The tour guide’s action is a preventative measure, but the unpleasant outcome would come from the shop’s owners, not the crowd, and would affect only the tour guide.  
E          This option contains neither a measure to prevent nor a measure to punish, and no connection is assumed between distributing fliers and supporting the candidate.

The correct answer is C.

8.   Last year sales tax in State Y was raised by 1%, with the additional revenues promised to fund improvements in education.  Representative Smith has proposed that the portion of sales tax revenues allotted to County X – some $5 million – be used to build additional schools and access roads in outlying areas, where even major streets are often impassable due to flooding. Representative Smith has already posted on his website blueprints detailing 3 new schools and 2 roadways designed to be unaffected by floods.

Which of the following, if true, represents the largest obstacle facing Representative Smith’s plan to use sales tax revenues to build additional schools in outlying areas of County X?

(A)       County X has rejected a proposal to establish toll stations along frequently-traveled roads in the county, even though funds raised were to be directed to Representative Smith’s project.
(B)       Students in County X currently travel an average of 20 miles in order to reach an existing school.
(C)       More densely populated counties in State Y will receive a larger percentage of the total revenues generated by the sales tax increase.
(D)       Provisions of the sales tax revenue rules allow funds to be used for any project impacting the education of at least 2% of students in County X.
(E)       The state has stipulated that sales tax revenues designated for education be used only for the construction or remodeling of school buildings, and curriculum improvements.

Evaluation of a Plan

Situation: A lawmaker proposes to use state money to build more schools in outlying areas of County X, where roads are often closed due to flooding.  The lawmaker’s plans include proposals for both schools and more dependable roads.

Reasoning: Which of the following is most damaging to the plan to build more schools? As the passage makes clear, the success of Representative Smith’s plan depends on the ability to complete two different construction projects: new schools and new roads.  If for any reason there will not be funding available for both of Representative Smith’s projects, his plan will likely not succeed.

A         This option, though it demonstrates a lack of additional financing, does not present an obstacle to Representative Smith’s plan as detailed in the passage.
B          This option may strengthen the argument for additional schools, but it does not directly address Representative Smith’s plan.
C          The amount of revenue directed to other counties in State Y is not directly relevant to a plan for County X.
D         This option would actually strengthen Representative Smith’s plan, because it would allow funds to be used for the construction of both schools and roadways.
E          Correct. This option correctly identifies the major shortcoming of Representative Smith’s plan: if the state will not allow funds to be used for the construction of new roads, then the plan to build both new schools and new means of access will likely fail.

The correct answer is E.

9.   Clean-burning coal power plants represent an improvement over traditional coal power plants because they are more efficient at capturing greenhouse gases before they are emitted into the atmosphere.

Although the large coal deposits of the Eastern United States make coal an economically cheap resource, the environmental damage caused by current methods of extraction makes coal an environmentally unwise choice as an energy source.

If the statements above are true, which of the following conclusions can be most properly drawn about clean-burning coal power plants?

(A)       Clean-burning coal power plants can prevent one type of environmental damage while indirectly causing another.
(B)       Environmental groups will protest the construction of more clean-burning coal power plants because they capture insufficient amounts of greenhouse gases.
(C)       In the long-term, the money saved by using inexpensive coal as an energy source will outweigh the cost of building more clean-burning power plants.
(D)       Most new clean-burning coal power plants will be built in the Eastern United States, where supplies of cheap coal are plentiful.
(E)       Most traditional coal power plants, especially those in the Eastern United States, will be demolished to make room for newer, clean-burning plants.

Argument Construction

Situation: Clean burning coal power plants emit fewer greenhouse gases that traditional coal burning power plants.  As an energy source, coal is inexpensive economically, but methods of extraction cause environmental damage.

Reasoning: Which conclusion can be drawn about clean burning coal power plants? Methods of extracting coal, according to the passage, cause environmental damage that outweighs coal’s usefulness as an inexpensive resource.  Any conclusions about clean burning coal power plants must take this possibility of environmental damage into account.

A         Correct. This statement properly recognizes the potential for environmental damage inherent in even clean burning coal power plants.
B          Environmental groups are not mentioned in either statement, nor is it suggested that clean burning power plants capture an insufficient amount of greenhouse gases.
C          The premises offer no information that can be used to directly compare the economic costs of coal extraction with the building of new clean burning coal power plants.
D         This conclusion does not take into account the necessary consideration of environmental damage.
E          The passage offers no information that can be used to reach this conclusion.

The correct answer is A.

10.       Charity Hospital Board Member: It does not make sense to continue pouring money into print advertising when telephone solicitation is a more effective fundraising method.  We currently employ three people full-time whose only job is to call families of former patients and ask them to donate.

EACH of the following, if true, undermines the argument that print advertising should be discontinued in favor of telephone solicitation EXCEPT

(A)       Funds paying the salaries of the telephone solicitors represent a slightly larger dollar amount than money received through their fundraising efforts.
(B)       Inaccurate record-keeping makes it difficult to determine what percentage of total fundraising dollars were raised according to which method.
(C)       A survey reveals that most of those who gave money to the hospital were first exposed to a fundraising ad in the newspaper and viewed the telephone call as a follow-up.
(D)       A survey reveals that most of those who gave money to the hospital did so because they had emotionally connected with a fundraiser over the telephone. 
(E)       A survey reveals that most of those who declined to donate to the hospital did so because they were offended by the approach of the telephone solicitors.

Argument Evaluation

Situation: A hospital board member argues that print advertising should be discontinued as a fundraising method because telephone solicitation is more cost-effective.

Reasoning: Which ONE of the following strengthens the argument that telephone solicitation is preferable to print advertising? The word except in the question stem signals that the correct answer will be the only one that does not undermine the argument presented in the passage.  The correct answer will demonstrate that telephone solicitation more effective.

A         This option undermines the argument by demonstrating that the hospital actually pays more in telephone solicitor salaries than the solicitors raise, leading to a net loss.    
B          This option undermines the argument by demonstrating that a comparison of print advertising and telephone solicitation cannot be made.
C          The argument is undermined here by a demonstration of the effectiveness of print advertising.
D         Correct. This option is the only one that strengthens the argument in the passage.  It demonstrates that most people who donated to the hospital did so because of a telephone solicitor.
E          The argument is undermined here by evidence that telephone solicitation is not only less effective, but counter-productive.

The correct answer is D.

1. The mayor of town T decided to lower the sales tax in order to boost retail sales in his town. The mayor believes that town T will eventually receive more sales tax as the result of the increased sales volume and can thereby afford a larger budget. The mayor wants to follow the example of town J, where such an experiment helped to increase the budget twice in a three year term.

Which of the following statements is the best proof that the opponents to the mayor's proposal can use in order to persuade the population of town T not to support this decision?

a) Town J is located very close to the borders of three other states, which causes residents of other states to shop in town J, as the sales taxes in those other states are higher than in this state. Town T is located far from any state border.

b) Town T is not big enough to make the difference of the sales tax received to budget positive as the result of the proposed change.

c) Town J has many industrial plants that purchase raw materials from the town's mines, unlike town T.

d) This kind of an experiment did not work in any other of the six towns that lowered the sales tax.

e) The mayor is corrupted by several groups of residents of town T. These groups are highly interested in lowering the sales tax as the move will make them much richer.

Explanation:
(A) Choice A. Provides a reasonable explanation of why the experiment worked in town J and why it would not work in town T. This is the correct answer.
b. Does not provide solid data, only makes an assumption.
c. Out of scope.
d. Does not provide sufficient information about those six other towns to enable clear comparison of town T with those six towns.
e. Out of scope.

2. Policies in the United States encourage high debt by offering a tax deduction for mortgage interest and discourage savings by taxing capital gains in investments. Nevertheless, U.S. policy isn't doesn't entirely encourage borrowing over savings because it has ______.

Which of the following best completes the idea above?

a) deductions for workers to reduce their annual tax burden

b) cut taxes on lower income workers

c) tax-free retirement savings programs

d) deductions for automobile and business expenses.

e) Federal Bank monetary policy to fight inflation and keep interest rates low.

Explanation:
The question is looking for a choice that demonstrates that U.S. policy is not entirely inimical to savings. So look for an answer choice that shows a policy that encourages savings and not borrowing. Choice (C) does this by eliminating savings on retirement. (A), (B) and (C) would increase income but not necessarily savings. (E) does clearly stabilize the economy, but low interest rates also encourage borrowing.

1.     Long-distance runners sometimes get shin splints from overtraining.  Shin splints are also common among freestyle skiers.  Freestyle skiers are also guilty of overtraining.

Which of the following, if true, most weakens the conclusion drawn above?

A.     Sprinters are also prone to getting shin splints.

B.      Freestyle skiers often exhibit other signs of overtraining such as dehydration.

C.    Long-distance runners are less prone to long-term stress injuries.

D.    Freestyle skiers get shin splints from landing jumps incorrectly.

E.     Freestyle skiers, on average, train fewer hours than do long distance runners.

Answer: D
This is a weaken question.  The passage tells us two facts, one about long-distance runners (they sometimes get shin splints from overtraining) and one about freestyle skiers (they also get shin splints).  The conclusion, that freestyle skiers must also over train, depends on the faulty assumption that because runners’ shin splints are caused by overtraining, skiers’ must be as well.  Choice A is irrelevant.  Choice B strengthens the conclusion.  Choice C is irrelevant.  Choice D pokes a hole in the assumption that the conclusion depends on: if skiers’ shin splints are not caused by overtraining, then it is not necessarily true that freestyle skiers are guilty of overtraining.  This weakens the conclusion considerably.  Choice E seems to weaken the conclusion by suggesting that freestyle skiers may be less likely to over train than are runners, but is in fact irrelevant.  Choice D is the best answer.  

EASY

2.     The mathematical constant ‘e’, the base of the natural logarithm, is transcendental, and is therefore irrational.  In 1882, the mathematician Johann Heinrich Lambert proved that the number ‘pi’ is irrational.  Pi must therefore be transcendental.

Which of the following statements, if true, most weakens the conclusion drawn above about the number pi

A.     The exact value of transcendental numbers cannot be given.

B.     The number √2 is irrational but not transcendental.

C.    The mathematician Fernard von Lindermann used the fact that e is transcendental to prove that pi is transcendental.

D.    The number √3 is transcendental but not irrational.

E.     It is extremely difficult to prove that a number is transcendental.

Answer: B
This question asks you to weaken the conclusion, which states that pi must be transcendental.  The key phrase here is “must be”: we know ‘e’ to be transcendental and therefore irrational, but all we’re told about pi is that it is irrational, so the conclusion that pi must therefore be irrational is unfounded.  Pi might be irrational (and in fact is), but the information in the passage can’t logically lead us to that conclusion.  A statement weakening the conclusion will show that pi is not necessarily transcendental.  Choices A, C and E are irrelevant. Choice B states that a number can be irrational and not transcendental; this shows that pi is therefore not necessarily transcendental.  Choice D gives us the reverse of what we want: it tells us that a number can be transcendental and not irrational.  We already know that pi is irrational, so this doesn’t weaken the conclusion.  Choice B does, and is the best answer.

            MEDIUM

3.    The ancient Greek word askesis, from which the adjective ‘ascetic’ derives, means practice, training, or exercise, and was originally used in reference to any sort of disciplined practice.   Today, the word ‘ascetic’ is primarily associated with the renunciation of worldly pursuits for the purpose of spiritual gain.  However, anyone can choose to practice asceticism.
Which of the following can be correctly inferred from the passage above

A.     The only people practicing asceticism today are monks, yogis or priests.

B.      Asceticism no longer refers to any disciplined practices other than those undertaken for spiritual gain.

C.    The ancient Greeks often incorporated principles of asceticism into their daily lives.

D.    The word ‘asceticism’ can be used independent of religious connotation.

E.     Ascetics consider worldly affairs more important than spiritual gain.

Answer: D
This question asks you to identify the statement that has been correctly inferred from the passage.  Because ‘infer,’ for GMAT purposes, is essentially synonymous with ‘must be true,’ the question is actually asking you to determine which statement can be logically derived from the information given in the passage.  Choices A and B are extreme; the passage states that the word ‘ascetic’ is primarily associated with religious ascetics, but there could be other types of ascetics as well.  Choice C incorrectly identifies the Greek word, ‘askesis,’ with the meaning of the English word ‘ascetic’.  Choice D is a correctly inferred statement: because the passage states both that ‘ascetic’ is only primarily associated with renouncing worldly pursuits for the spiritual, and because it further says that ‘anyone’ can choose to practice asceticism, it must therefore be true that ‘asceticism’ is not used exclusively to refer to a religious practice. Choice E is the opposite of what is stated in the passage.  Choice D is the only statement that can be logically inferred from the passage, and is the best answer.

7. In response to an overwhelming demand for better technical support, we have added an online help section to our website where customers can chat live with customer service representatives.  We are confident that this will significantly decrease the number and frequency of complaints about our technical support.

The company’s plan assumes which of the following?

A.     Customers will not have other complaints.

B.     All of their customers have access to the internet.

C.    Customer service representatives can provide technical support.

D.    Online support will be equally as effective as telephone support.

E.     Customers are less likely to complain via email than by telephone.

Answer: C
This question asks you to identify the assumption in the company’s plan to improve technical support.  This is another way of asking what the plan depends on: if the reverse were true, would the plan still work as intended?  Choice A is out of scope: the company’s plan is intended to reduce technical support complaints only.  Choices B and D are extreme: only some customers need to have internet access for the plan to work, not all customers; and online support need only be effective, not as effective as telephone support.  Choice C is a necessary assumption: if customer service reps can’t provide technical support, then this service will not address customers’ technical support concerns.  Choice E is irrelevant; while this may impact the number and frequency of complaints in some way, it has no bearing on the efficacy of the plan itself.  Choice C is the best answer.

EASY/MEDIUM

8. Though some reports have called the People’s Republic of China’s recently instated property law their first piece of legislation addressing the individual’s right to own private assets, this is not true; the right to private property was in fact written into the Constitution of the People’s Republic of China four years ago, in 2003.

 The bolded phrase plays which of the following roles in the passage above?

A.     Answer to a question

B.     Correction of a misconception

C.    Refutation of a known fact

D.    Support for a claim

E.     Statement of identity

Answer: D
This question asks you to identify the reasoning in the passage.  The unbolded portion of the passage contains a claim that reports about the new law in China are incorrect.  The bolded portion contains support for that claim.  Choice D is the best answer.  Choices A, B and E do not describe the role played by the bolded phrase.  Choice B describes the passage as a whole.  Choice D is correct.

HARD

11. In the secretarial schools of the mid-20th century, accuracy of typing was valued as much as speed.  Business letters were supposed to be error-free with no visible corrections, and on typing tests, deductions were made from the speed scoring for every error found.  The development of so many varieties of correction methods and technologies in this time period is therefore somewhat of a mystery.

Which of the following, if true, would most weaken the conclusion drawn above?

A.     Business letters were typed on a heavyweight paper that not only looked good, but could endure repeated erasure.

B.     A special kind of typewriter paper called erasable bond was invented to allow easier removal of type from the page.

C.    Typewriters are more difficult to type on than keyboards, and even the most sophisticated typewriters would sometimes jam.

D.    In the mid-20th century, typewriters were as ubiquitous as computers are today.

E.     Typing mistakes were considered sufficient reason for firing a secretary.

Answer: D
This question asks you to weaken the conclusion reached by the author about typewriter correction methods.  The passage states that typing accuracy was highly prized in secretarial schools, and that therefore the development of correction methods is a mystery.  This conclusion can be weakened by providing evidence that there were valid reasons for the development of correction methods.  Choices A and B are irrelevant; they merely provide information about certain kinds of correction methods.  Choice C weakens the conclusion somewhat; it suggests that even sophisticated typists could make mistakes, but still doesn’t provide a reason for the invention of many types of correction methods.  Choice D weakens the conclusion considerably.  If typewriters were as widespread as computers are today, that means that almost everyone had one and that correction methods could have been invented for the average typist, regardless of professional secretarial standards.  Choice E weakens the conclusion somewhat.  Choice D weakens the conclusion the most, and is therefore the best answer.

MEDIUM

12. Felicia: Internships are a waste of time and energy.  In the time you spend working for free, you could be temping or taking classes or pursuing employment that not only fulfills your interests, but also compensates you for your hard work.

Nitesh: The purpose of internships isn’t compensation, it’s preparation for a future career.  With an internship, you can secure connections within your field of choice and also gain experience that looks great on a resume.

Nitesh objects to Felicia’s argument by

A.     correcting a common perception

B.     pointing out an error of logic

C.    refuting a previously agreed-upon conclusion

D.    objecting to an unstated premise

E.     suggesting an alternative definition

Answer: D
This question asks you to identify the reasoning in Nitesh’s response to Felicia’s argument, which proposes that internships are not in fact a waste of time, as Felicia has suggested.  Felicia’s argument begins with her conclusion (“Internships are a waste of time and energy”) and is followed by support for her conclusion.  Nitesh’s argument responds to Felicia’s unstated premise that the purpose of all work is compensation by suggesting that internships are a form of preparation, not employment per se.  Choice D correctly identifies Nitesh’s method of objection.  Choice A is inaccurate; while he may be correcting a common perception, that’s not the point of his objection in context.  Choice B is correct in a sense because Nitesh is objecting to Felicia’s failure to secure her premises, but he does not say that she failed to do this; he simply states his objection.  Choice C is inaccurate in that we don’t know the content of their previous discussion.  Choice E is incorrect because they are not debating a definition.  Choice D accurately states Nitesh’s method of objection, and is the best answer.

MEDIUM

 16.  A chemical leak at a local factory contaminated the water at a nearby fishing area.  To compensate for the damage they caused to the river, the factory has announced their intention to donate a large sum of money to local environmental conservation efforts.

The factory’s inadequate method of compensation was most likely caused by which of the following errors of reasoning?

A. Mistaking cause for effect
B. Equating a part with the whole
C. Miscalculating a value
D. Misapplying a principle
E. Ignoring a premise

Answer: B
This question asks you to identify an error in reasoning.  The error lies in the method of compensation decided upon by the factory; in donating to the general cause of conservation in the area instead of giving the money directly to the fishing area, they failed to correct the damage they caused to that specific area of land. Choice B describes this best, as the money will be spent on all of the land in the area instead of the part contaminated by the chemical leak.  Choice B is the best answer.

MEDIUM

19. With the exception of Professor Kirschner, all faculty in the History department are either tenured or under thirty-five. 

From which of the following can the statement above most correctly be inferred?

A.     Professor Kirschner is the only professor in the History department who is not tenured.

B.     If a professor in the History department is under thirty-five or tenured, then he or she is not Professor Kirchner.

C.    Professor Kirchner is the only professor in the History department who is over thirty-five and lacks tenure.

D.    If a professor is in the History department, then he or she is either tenured or under thirty-five, or is Professor Kirschner.

E.     Professor Kirschner cannot be a member of the History department.

Answer: C
This question asks you to find the statement from which the sentence about Professor Kirschner can be inferred.  The sentence tells us that among the faculty in the history department, everyone except Professor Kirscher is either tenured or under thirty-five.  This means that, with the exception of Professor Kirchner, a professor in the history department is either tenured or under thirty-five.   Choice A will not lead us to that conclusion; it says that Professor Kirchner is the only professor who is not tenured, but we know that the professors who are under thirty-five are not tenured.  Choice B is incorrect because it leaves open the possibility that professors can be both under thirty-five and tenured.  Choice C is an inference that can be drawn from the statement; however, the statement about Professor Kirchner cannot be inferred from it.  Choice D contains the same information found in the statement about Professor Kirschner, just rearranged.  There are three types of professors: those who are tenured, those who are under thirty-five, and those who are neither (only Professor Kirchner!).  This information is present in both the statement and choice D; choice D is therefore a logical source of the inferred statement.  Choice E is nonsense.  Choice D contains the only sentence from which the statement can be inferred, and is therefore the best answer.