x<y?

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by Anurag@Gurome » Mon Aug 20, 2012 10:39 pm
grandh01 wrote:Is x less than y?
(1) x-y+1<0
(2) x-y-1<0
Question: Is x < y? or Is x - y < 0?

(1) x - y + 1 < 0 or x - y < -1, which implies that x - y < 0; SUFFICIENT.

(2) x - y - 1 < 0 or x - y < 1, which implies that x - y may or may not be < 0; NOT sufficient.

The correct answer is A.
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by Brent@GMATPrepNow » Tue Aug 21, 2012 6:54 am
grandh01 wrote:Is x less than y?
(1) x-y+1<0
(2) x-y-1<0
Target question: Is x < y?

Statement 1: x-y+1<0
Add y to both sides to get x+1 < y

Big point: x < x+1

When we combine the two inequalities, we get x < x+1 < y
From this, we can definitely see that x < y
So, statement 1 is SUFFICIENT


Statement 2: x-y-1<0
Add y to both sides to get x-1 < y

Big point: x-1 < x

In this instance, we can see that y and x are both greater than x-1
Given this, we cannot tell whether x < y
So, statement 2 is NOT SUFFICIENT

Answer = A

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Brent
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