Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 350,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: Given that X, Y, Z are non zero integers. Is X^3Y^5Z^4>0? [#permalink]
25 Aug 2012, 04:19

1

This post received KUDOS

Expert's post

Given that X, Y, Z are non zero integers. Is (X^3)(Y^5)(Z^4)>0?

Notice that since z is a non-zero integer, then z^4>0, so we can reduce the given inequality by it and the question becomes: is x^3*y^5>0? or: is xy>0?

(1) XY > Z^4 --> since z^4>0, then we have that xy>z^4>0. Sufficient. (2) X > Z. Not sufficient as we don't know anything about y.

Re: Given that X, Y, Z are non zero integers. Is X^3Y^5Z^4>0? [#permalink]
25 Aug 2012, 04:23

1

This post received KUDOS

vinay911 wrote:

Given that X, Y, Z are non zero integers. Is (X^3)(Y^5)(Z^4)>0?

(1) XY > Z^4 (2) X > Z

The sign of the given expression depends on the sign of the product \(XY\) because \(X^3Y^5Z^4=XY*X^2Y^4Z^4\) and \(X^2Y^4Z^4\) is always non-negative. The given product can be 0 as well, if at least one of the variables is 0.

(1) Not sufficient, because Z can be 0. (2) Not sufficient, because Z can be 0.

(1) and (2): Although from (1) we can deduce that \(XY>0,\) (because \(Z^4\geq0\)) again not sufficient, the same fast reasoning, Z can still be 0. _________________

PhD in Applied Mathematics Love GMAT Quant questions and running.

Re: Given that X, Y, Z are non zero integers. Is X^3Y^5Z^4>0? [#permalink]
25 Aug 2012, 04:34

Expert's post

EvaJager wrote:

vinay911 wrote:

Given that X, Y, Z are non zero integers. Is (X^3)(Y^5)(Z^4)>0?

(1) XY > Z^4 (2) X > Z

The sign of the given expression depends on the sign of the product \(XY\) because \(X^3Y^5Z^4=XY*X^2Y^4Z^4\) and \(X^2Y^4Z^4\) is always non-negative. The given product can be 0 as well, if at least one of the variables is 0.

(1) Not sufficient, because Z can be 0. (2) Not sufficient, because Z can be 0.

(1) and (2): Although from (1) we can deduce that \(XY>0,\) (because \(Z^4\geq0\)) again not sufficient, the same fast reasoning, Z can still be 0.

Eva, notice that we are told that X, Y, Z are non zero integers. _________________

Re: Given that X, Y, Z are non zero integers. Is X^3Y^5Z^4>0? [#permalink]
25 Aug 2012, 04:47

Bunuel wrote:

EvaJager wrote:

vinay911 wrote:

Given that X, Y, Z are non zero integers. Is (X^3)(Y^5)(Z^4)>0?

(1) XY > Z^4 (2) X > Z

The sign of the given expression depends on the sign of the product \(XY\) because \(X^3Y^5Z^4=XY*X^2Y^4Z^4\) and \(X^2Y^4Z^4\) is always non-negative. The given product can be 0 as well, if at least one of the variables is 0.

(1) Not sufficient, because Z can be 0. (2) Not sufficient, because Z can be 0.

(1) and (2): Although from (1) we can deduce that \(XY>0,\) (because \(Z^4\geq0\)) again not sufficient, the same fast reasoning, Z can still be 0.

Eva, notice that we are told that X, Y, Z are non zero integers.

Oooooops! Thanks.

So, forget about any of the variables being 0. We need to check whether \(XY>0.\) Then the above solution changes:

(1) Sufficient, since \(XY>0,\) (because \(Z^4>0\)). (2) Not sufficient, as we don't know anything about Y.

Answer A _________________

PhD in Applied Mathematics Love GMAT Quant questions and running.

Re: Given that X, Y, Z are non zero integers. Is X^3Y^5Z^4>0? [#permalink]
26 Aug 2012, 09:34

Given that X, Y, Z are non zero integers. Is (X^3)(Y^5)(Z^4)>0?

(1) XY > Z^4 (2) X > Z

My approach :-

(i) XY>Z^4 RHS is always +ve , so XY both can either be +ve or -ve a)if XY both +ve then (X^3)(Y^5)(Z^4)>0 (because Z^4 is +ve b)if XY both -ve then (X^3)(Y^5)(Z^4)>0 (because - - + is +ve

Suffficient

(ii) no clue about Y -insufficient

(A) wins _________________

" Make more efforts " Press Kudos if you liked my post

Hello everyone! Researching, networking, and understanding the “feel” for a school are all part of the essential journey to a top MBA. Wouldn’t it be great... ...

I have not posted in more than a month! It has been a super busy period, wrapping things up at Universal Music, completing most of the admin tasks in preparation for Stanford...