Math questions from any Manhattan Prep GMAT Computer Adaptive Test.
galanti.yosef
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Amp it Up

by galanti.yosef Wed Aug 24, 2011 3:21 pm

Here's a DS problem from the Question Bank that I'm having trouble with:

Is mp greater than m?
(1) m > p > 0

(2) p is less than 1

I got it wrong because I rephrased into:
"Is mp>m? = Is p>m/m? = Is p>1?"

So 1) is insufficient, and 2) is sufficient in answering the question after my rephrasing. I picked B.

The correct answer is C though and I understand how they did it, but I don't know why my rephrase/simplifying didn't work. Can you guys help me understand that?

Thanks!
Joe
mithunsam
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Re: Amp it Up

by mithunsam Wed Aug 24, 2011 5:28 pm

Question didn't say whether p is +ve or -ve. So, we need to consider two cases 1) p is +ve 2) p is -ve

p is +ve (and m +ve)
mp>m ? => p>m/m ? => p>1 ?

p is -ve (and m +ve)

m*-p>m ? => -p>m/m ? => -p>1 ? => p<-1?

[There are other cases like m is +ve/-ve, p&m are of same sign or not. But all cases will fall under one of the above two scenarios].

A or B alone is insufficient
Together, they are sufficient.
tim
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Re: Amp it Up

by tim Sat Sep 24, 2011 1:12 pm

thanks..
Tim Sanders
Manhattan GMAT Instructor

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