Source: Official Guide for GMAT Review 2016 Data Sufficiency ; #54

3

Is zp negative?

Is zp negative?

1 Explanation

1

Danny Watts Jr

Statement 1: pz^4 < 0; z^4 will always be a positive number, so p must be negative in order for the solution to be less than 0. However, z itself can be negative or positive, so NOT SUFFICIENT.

Statement 2: p + z^4 = 14. If z = 1 or -1, then p would be positive (13). P would be negative for another result though, so this statement is NOT SUFFICIENT.

Together: P is negative based on statement 1, but neither of the two statements give us a definitive sign for Z. As a result, the statements together or NOT SUFFICIENT, so the answer is (E).

Jan 6, 2018 • Comment

David Recine, Magoosh Tutor

Daniel's got it! Statement 1 is insufficient due to number properties-- negative x and positive x will both produce a positive number if raised to an even power.

And for statement 2, it's a matter of testing cases. You can plug in p and z values that get you a negative number for pz or a positive number for pz.

Jan 8, 2018 • Reply

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Official Guide for GMAT Review 2016

Official Guide for the GMAT 2015 14th Ed.

Official Guide for the GMAT 13th Ed.

Official Guide for the GMAT 12th Ed.

Revised GRE PDF 2nd Ed.


Section 6.3 Data Sufficiency

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