Math questions from any Manhattan Prep GMAT Computer Adaptive Test.
aps_asks
Forum Guests
 
Posts: 137
Joined: Fri Jul 09, 2010 9:32 pm
 

A MGMAT Inequality Question

by aps_asks Wed May 23, 2012 6:33 am

Is q > t ?

(1) qp2 < tp2

(2) qp3 > tp3

The answer to the above Question is A) ...But if i rephase Question
Is q > t ?

(1) qp2 <= tp2

(2) qp3 > tp3

What should be the answer...I think it should be E )......Bcoz in that case P can be zero and the first statement has two possibilities
1) q<t
2) 0=0

Please let me know your comments.
manhattanmani
Students
 
Posts: 4
Joined: Thu Dec 22, 2011 10:56 pm
 

Re: A MGMAT Inequality Question

by manhattanmani Wed May 23, 2012 7:57 am

is q>t?
st.1) qp2<tp2
= q<t
sufficient

s.2 ) qp3>tp3
= q>t
sufficient

so the answer will be D - please correct me where i m wrong.

likewise i get B when you are rephrasing.
which imp property am i missing?
jnelson0612
ManhattanGMAT Staff
 
Posts: 2664
Joined: Fri Feb 05, 2010 10:57 am
 

Re: A MGMAT Inequality Question

by jnelson0612 Sun May 27, 2012 5:11 pm

aps_asks Wrote:Is q > t ?

(1) qp2 < tp2

(2) qp3 > tp3

The answer to the above Question is A) ...But if i rephase Question
Is q > t ?

(1) qp2 <= tp2

(2) qp3 > tp3

What should be the answer...I think it should be E )......Bcoz in that case P can be zero and the first statement has two possibilities
1) q<t
2) 0=0

Please let me know your comments.


Here's the thing: statements are always true. You can count on them as fact. Because of that, you should determine what additional information you can draw from them.

Statement 1 tells you that qp^2 < tp^2. If p were zero, then qp^2 and tp^2 would also be zero and they would be equal to each other. However, they are not equal. Thus, p cannot be zero. If p is not zero, then p^2 MUST be positive, since squaring either a negative or positive number results in a positive number. So now let's look at what we have:

q * (some positive number) < t * (some positive number)

I can divide an identical positive number out of both sides of an inequality without disrupting the inequality. Thus, I divide that positive out and statement 1 tells me that q < t. Sufficient.
Jamie Nelson
ManhattanGMAT Instructor