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Is x > y

by kamalakarthi » Thu Jul 31, 2014 3:46 pm
Is x > y?

(1) x - y > 3

(2) x + y > 3

I am able to understand statement 1 is sufficient but not able to understand why statement 2 is not sufficient...

I can understand from statement 1 that x > 3+y so x must greater than y
but if I use x > 3-y ,I am thinking that it is still greater than x...Can u help me understand why this is not correct...

Can you please help.
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Source: — Data Sufficiency |

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by Brent@GMATPrepNow » Thu Jul 31, 2014 4:22 pm
kamalakarthi wrote:Is x > y?

(1) x - y > 3
(2) x + y > 3

Target question: Is x > y?

Statement 1: x - y > 3
Add y to both sides to get: x > y + 3
Important: We also know that y + 3 > y
So, we can combine both inequalities to get: x > y + 3 > y
Here, we can clearly see that x > y
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: x + y > 3
There are several values of x and y that satisfy this condition. Here are two:
Case a: x = 5 and y = 2, in which case x + y > 3. In this case, x > y
Case b: x = 2 and y = 5, in which case x + y > 3. In this case, x < y
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

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by sapuna » Fri Aug 01, 2014 12:49 am
kamalakarthi wrote:Is x > y?

(1) x - y > 3

(2) x + y > 3

I am able to understand statement 1 is sufficient but not able to understand why statement 2 is not sufficient...

I can understand from statement 1 that x > 3+y so x must greater than y
but if I use x > 3-y ,I am thinking that it is still greater than x...Can u help me understand why this is not correct...

Can you please help.
Statement 1 will always be sufficient because we get x > y + 3. Regardless of the values of x and y (whether they are both positive , both negative, or x is positive and y is negative) x will always be > y because of the given inequality

Using statement 2 we get x > 3 - y. Not the same case as statement 1.

plug in some values if you can`t guess ti right away. x = 5 y =1 = > x > y
However, there are some different options. x = 1 y = 3 x > 3- y but y > x so statement 2 is not sufficient
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by GMATinsight » Fri Aug 01, 2014 9:14 am
kamalakarthi wrote:Is x > y?

(1) x - y > 3

(2) x + y > 3

I am able to understand statement 1 is sufficient but not able to understand why statement 2 is not sufficient...

I can understand from statement 1 that x > 3+y so x must greater than y
but if I use x > 3-y ,I am thinking that it is still greater than x...Can u help me understand why this is not correct...

Can you please help.
Statement 2)x + y > 3

@x=1, y=3 : 1+3 > 3 and x < y
@x=3, y=1 : 3+1 > 3 and x > y
INSUFFICIENT

I hope this makes it clearer using Numbers
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