Source: Official Guide for GMAT Review 2016 Data Sufficiency ; #20


What is the value of w^(-2)?

What is the value of w^(-2)?

2 Explanations



(1) since w^ (-1) = 2^(-1),
then w^(-2) = w^(-1)(2)
= 2^(-1)(2) = 4^(-1)

(2) i don't know how to interprete this. pls. explain this to me...tx

Nov 5, 2016 • Comment

Sam Kinsman, Magoosh Tutor

Hi Amure,

You're right that from statement 1, we can conclude that w^(?2) is 1/4 (or 4^(-1)).

Statement 2 says that w^3 = 8. Since 2^3 = 2*2*2 = 8, we know that w must be equal to 2. So w = 2, and therefore w^(?2) = 2^(-2) = 1/4.

Both statements by themselves are sufficient, and the answer is D

Nov 11, 2016 • Reply


Nicholas Dureault

This question has a mistake in it - be warned.

The prompt is: What is the value of W^(-2)

1) w^(-1) = 1/2
2) w^(8) = 8

for 2, what they meant to say (and is in the answer key) is:
2) 2^(3) = 8

Jan 14, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Thanks for your message! I've let the content editors know so that this can be corrected. Since we're a small team, it may some time to change that. However, in the meantime, your comment will help other students who visit the forum! Thanks again :)

Jan 15, 2016 • 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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