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Can anyone help me with this GMATPrep DS question?

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Can anyone help me with this GMATPrep DS question?

by abhijeet_g » Tue Apr 23, 2013 9:06 am
Is w greater than 1?

1. w+2 > 0
2. w^2 > 1

My approach:

1. w+2 >0 then w> -2 Not sufficient
2. w^2 > 1 then w >1 or w < -1. Not sufficient

Combining 1 & 2, we get -2 < w < -1 and hence w < 1. My answer : C

But OA is E. Can anyone explain?[/b]
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by Zarrolou » Tue Apr 23, 2013 9:12 am
1. w+2 >0 then w> -2 Not sufficient
2. w^2 > 1 then w >1 or w < -1. Not sufficient

Combining 1 & 2, we get -2 < w < -1 OR w>1.(<-you missed this interval)

E as you see.
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by abhijeet_g » Tue Apr 23, 2013 9:15 am
Yeah ... I did realize it but after posting and thinking for a minute...Anyways thanks for the input :-)
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by Brent@GMATPrepNow » Tue Apr 23, 2013 10:54 am
abhijeet_g wrote:Is w greater than 1?

1. w+2 > 0
2. w^2 > 1
If you have a feeling that a statement is not sufficient, you can look for contradictory cases.

Target question: Is w greater than 1?

Statement 1: w+2 > 0
There are several values of w that meet this condition. Here are two:
Case a: w = 2, in which case w is greater than 1
Case b: w = -1.5, in which case w is not greater than 1
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: w^2 > 1
There are several values of w that meet this condition. Here are two:
Case a: w = 2, in which case w is greater than 1
Case b: w = -1.5, in which case w is not greater than 1
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined:
There are several values of w that meet both conditions. Here are two:
Case a: w = 2, in which case w is greater than 1
Case b: w = -1.5, in which case w is not greater than 1
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer = E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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