Data Sufficiency

Does w - v = 0?

(1) w² - v² = 0
(2) wv < 0

Answer: B
Source: www.gmatprepnow.com

[email protected] wrote: ↑

Tue Oct 18, 2022 5:43 am

Does w - v = 0?

(1) w² - v² = 0
(2) wv < 0

Answer: B
Source: www.gmatprepnow.com

Target question: Does w - v = 0?
This is a good candidate for rephrasing the target question.
If we add v to both sides of the target question, we get...
REPHRASED target question: Does w = v?

Aside: Here’s a video with tips on rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100

Statement 1: w² - v² = 0
There are infinitely many values of w and v that satisfy statement 1. Here are two:
Case a: w = 3 and v = 3. In this case, the answer to the REPHRASED target question is YES, w equals v
Case b: w = 3 and v = -3. In this case, the answer to the REPHRASED target question is NO, w does not equal v
Since we can’t answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: wv < 0
If wv is negative, then one value (w or v) is POSITIVE, and the other value is NEGATIVE.
Since w and v are different signs, w and v cannot be equal
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

Cheers,
Brent