a data from gmatclub

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a data from gmatclub

by diebeatsthegmat » Tue May 10, 2011 10:07 pm
If w + x < 0, is w - y > 0 ?

1) x + y < 0

2) y < x < w

[spoiler]i know B is sufficient but why A is not? if x+w< o (1) and x+y<0 (2) we can take (1)-(2) <=> w-y< o and sufficient.
why the answer cant be D?
[/spoiler]
Source: — Data Sufficiency |

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by sourabh33 » Wed May 11, 2011 12:05 am
For Statement 1

When W = -5, X = -5, Y = 4 then w+x = -10 <0 , x+y = -1 <0, w-y=-9 < 0
When W = 5, X = -6, Y = -7 then w+x = -1<0 , x+y = -1 <0, w-y= 12 > 0
When W = 5, X = -6, Y = 5 then w+x = -1<0 , x+y = -1 <0, w-y= 0 = 0

There statement 1 is insufficient as w-y can have multiple solutions when x+y<0
Last edited by sourabh33 on Wed May 11, 2011 6:40 am, edited 1 time in total.

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by GMATGuruNY » Wed May 11, 2011 4:33 am
diebeatsthegmat wrote:If w + x < 0, is w - y > 0 ?

1) x + y < 0

2) y < x < w

[spoiler]i know B is sufficient but why A is not? if x+w< o (1) and x+y<0 (2) we can take (1)-(2) <=> w-y< o and sufficient.
why the answer cant be D?
[/spoiler]
Is w-y > 0?

Question rephrased: Is w > y?

Statement 1: x+y < 0.
Rewritten, y < -x.
Rewritten, w+x < 0 becomes w < -x.
Now we can see that both w and y are less than -x, but no information is given about whether w>y.
Insufficient.

Statement 2: y < x < w.
Thus, y < w.
Sufficient.

The correct answer is B.
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