kushal.adhia wrote:The average (arithmetic mean) of the 43 numbers in list L is a positive number. The average of all 48 numbers in both lists L and M is 50 percent greater than the average of the 43 numbers in list L. What percent greater than the average of the numbers in list L is the average of the numbers in list M?
A. 85%
B. 240%
C. 350%
D. 480%
E. 580%
OA is D
Good math solutions (especially the first one - picking numbers is a great way to tackle this type of question), let's take a strategic approach instead.
We know that adding a set of only 5 numbers to a set of 43 numbers increases the average by 50%. So, those 5 numbers must be considerably bigger than the average of the other set: eliminate A and B.
We also know that the question is asking "What percent greater ". Whenever a question asks "what percent greater", there's almost always a wrong answer to punish people for answering the question "what percent of" instead. Now, the difference between "what percent greater" and "what percent of" is exactly 100%. Are there two choices that are 100% apart? Yes!
So, we identify E as the trap answer and D as the correct answer: choose D.
Everything about the GMAT is standardized, including the traps - the better you know how the testmaker thinks, the more you can use that information to your advantage.
