BTGModeratorVI wrote: ↑Tue May 12, 2020 2:11 pm
If x = y + z, is x > y ?
(1) y > 0
(2) z > 0
Answer:
B
Source: Official guide
Given: Given x = y + z
Target question: Is x > y ?
This is a good candidate for
rephrasing the target question.
Take
x > y, and subtract y from both sides to get:
x - y > 0
So, asking
Is x > y? is the SAME AS asking
Is x - y > 0?
REPHRASED target question: Is x - y >?
Aside: Here’s a video with tips on rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100
Statement 1: y > 0
There are several values of x, y and z that satisfy statement 1. Here are two:
Case a: x = 3, y = 2 and z = 1 (this satisfies the given condition that x = y + z. In this case, x - y = 3 - 2 = 1. So, the answer to the REPHRASED target question is
YES, x - y IS greater than 0
Case b: x = 2, y = 3 and z = -1 (this satisfies the given condition that x = y + z. In this case, x - y = 2 - 3 = -1. So, the answer to the REPHRASED target question is
NO, x - y is NOT greater than 0
Since we cannot answer the
REPHRASED target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: z > 0
It's given that x = y + z
This means that x - y = z
Since statement 1 tells us that z > 0, then it is the case that
x - y > 0
PERFECT!!
The answer to the REPHRASED target question is
YES, x - y IS greater than 0
Since we can answer the
REPHRASED target question with certainty, statement 2 is SUFFICIENT
Answer: B
Cheers,
Brent
