Bunuel wrote:
If the sum of all consecutive integers from A to B (A<B), inclusive, is S and the average (arithmetic mean) of these integers is M, then, in terms of A, B, and S, what is the value of M?
A. 2S/(A+B+1)
B. 2S/(A+B)
C. (B−A)/2
D. S/(B−A+1)
E. (B−A)/(2S)
Any time there are variables in the question that are repeated in the answer choices, I look to see if there's an opportunity to Plug In.
Let's make A=1 and B=4. S=10 and M=2.5. Plug those into the answer choices.
(A) 20/6 Wrong
(B) 20/5 Wrong
(C) 3/2 Wrong
(D) 10/4 Keep it
(E) 3/20 Wrong
Answer choice D.
ThatDudeKnowsPluggingIn
_________________
GMAT/GRE Tutor -
http://www.thatdudeknows.comFormer GMAT Master Trainer (trained new GMAT instructors) for The Princeton Review.
B-schools couldn't care less about most of the content on the GMAT; the content is just a way to test
how you think, not what you know. The two main sections of the GMAT are NOT Quantitative and Verbal. They are Quantitative REASONING and Verbal REASONING. Between the two section names, "Reasoning" appears twice; "Quantitative" and "Verbal" each appears once. ;)
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