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Is x > y?

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Source: — Data Sufficiency |

Re: Is x > y?

by Brent@GMATPrepNow » Sat May 16, 2020 8:27 am
BTGModeratorVI wrote:
Sat May 16, 2020 7:33 am
Is x > y?

(1) x - y - 1 > 0
(2) x - y + 1 > 0

Answer: A
Source: Magoosh
Target question: Is x > y?

Statement 1: x - y - 1 > 0
Add y and add 1 to both sides to get: x > y + 1
Since we can also say that y + 1 > y for all values of y, we can write: x > y + 1 > y
At this point, we can see that x > y
The answer to the target question is YES, x is greater than y
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: x - y + 1 > 0
Add y to both sides to get: x + 1 > y
There are several values of x and y that satisfy the inequality x + 1 > y. Here are two:
Case a: x = 10 and y = 0. In this case, the answer to the target question is YES, x is greater than y
Case b: x = 0.5 and y = 1. In this case, the answer to the target question is NO, x is not greater than y
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer: A

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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