The above graph lists the monthly sales (in $100,000 increments) at a car dealership. For January and February, the dealership had two sales agents. The dealership added a sales agent in March and one more in May. What was the percent increase in sales per agent in June compared to January?
A. 50% B. 100% C. 125% D. 200% E. 400%
(B) In January, the dealership had 2 agents and had sales of $200,000, or $100,000 per agent. An agent was added to the sales force in March (making 3) and then one more was added in May (making 4). This leaves 4 agents on the sales force for June, when the dealership sold $800,000 or $200,000 per agent ($800,000/4). We can find the percent difference by dividing the difference between the two peragent amounts by the peragent amount in January: Percent Difference = ($200,000 – $100,000) / ($100,000)= 100,000 ÷ 100,000 = 1 or 100%. The correct answer is choice (B).
The trap answer is choice (D). $200,000 per agent is double $100,000 per agent. But remember that the question asks for the percent increase. $200,000 represents 200% of $100,000, but only 100% more than $100,000. 
In this question in May the chart says 900,000 not 800,000 which would make the answer C.
