gmat preparation courses

It is currently Sun Jul 22, 2018 10:10 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: GMAT Percentage (Data Sufficiency)
PostPosted: Tue Jul 27, 2010 4:45 am 
Offline

Joined: Sun May 30, 2010 3:15 am
Posts: 424
What percentage of families in the state have annual incomes over $50,000 and have a net worth over $500,000?
(1) 65% of all the families in the state have an annual income over $50,000.
(2) 20% of the families in the state with an annual income over $50,000 have a net worth above $500,000.

A. Statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not.
B. Statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not.
C. Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient.
D. Either statement BY ITSELF is sufficient to answer the question.
E. Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, meaning that further information would be needed to answer the question.


(C) Statement (1) alone is not sufficient, because it only gives us the percentage of families in the state with the required annual income, but gives no information regarding the net worth.

Statement (2) is not sufficient because, although it tells you about the percentage of families that satisfy the question, it does not give you the percentage of families in the state that have an annual income of $50,000.

Statements (1) and (2) COMBINED are sufficient. 20% of the 65% are families who both have annual incomes over $50,000 AND have a net worth above $500,000. To find out the percentage of people with both traits, multiply the two independent variables. The two statements give these two variables.

Remember, however, that for these questions you do not need to solve for an answer; you simply need to establish whether or not you have sufficient information to do so.
-------------

I am confused by the wording of the question.
Should not statement 2 be sufficient here since it satisfies both requirements?


Top
 Profile  
 
 Post subject: Re: math (test 5, question 7): data sufficiency, percentages
PostPosted: Tue Jul 27, 2010 5:30 am 
Offline

Joined: Sun May 30, 2010 2:23 am
Posts: 498
Looking at Venn diagram when solving this question may help you to understand it better.
Image

That is what we know when use statement (2) by itself:
Image

Note that we know only that families in the state that have annual incomes over $50,000 and have a net worth over $500,000 (painted in dark) make 20% of the families in the state with an annual income over $50,000. But what percentage does it make out of total? We do not know, because we do not know what percentage out of total make families with an annual income over $50,000. Is 100%, or 50% or anything else?
Image

But when we use statement (1) together with statement (2) we can answer the question:
Image


Attachments:
venn_diagram.gif [11.79 KiB]
Not downloaded yet
statement2_and_1.gif [12.61 KiB]
Not downloaded yet
statement2_dontknow.gif [12.64 KiB]
Not downloaded yet
statement2.gif [12.61 KiB]
Not downloaded yet
Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group