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Mcgraw hills gmat 2008 practice test

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Mcgraw hills gmat 2008 practice test

by tanay006 » Mon May 25, 2009 12:08 pm
In a nationwide poll, P people were asked
2 questions. If 2/5 answered “yes” to question 1,
and of those 1/3 also answered “yes” to
question 2, which of the following represents
the number of people polled who did not
answer “yes” to both questions?
A. 2/15 P
B. 3/5 P
C. 3/4 P
D. 5/6 P
E. 13/15 P
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by dmateer25 » Mon May 25, 2009 5:07 pm
Here are a couple ways to solve this one.

First algebraically:

P people were asked 2 questions. 2/5 answered yes to the first question.

So, P(2/5) answered Yes.

Of these people that answered yes to the first question, 1/3 answered yes to the second question.

So (2p/5) * (1/3) = 2P/15

So 2P/15 are the people who answered Yes to both questions. We want to know how many people didn't answer yes to both questions so P - 2P/15 = 13P/15

E.


Now solving this picking a smart number.

15 is the smart number since the denominators are 3 and 5 that we are working with.

So we will say 15 people were asked the 2 questions.

15 * 2/5 = 6 answered yes to the first

6 * 1/3 = 2 answered yes to both

15 - 2 = 13 didn't answer yes to both.

Fill in 15 for P in the answer choice and see which one results in 13. E is the only one.
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