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Is W greater than 1?

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dianapaolasanchez
 Post subject: Is W greater than 1?
 Post Posted: Sun Jun 27, 2010 6:56 pm 
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Course Students


Posts: 21
Is W greater than 1?

1) w+2>0
2) w^2>1

rephrase:

W > 1 ?

First Statement:
w+2 > 0
W > -2
Insufficient

Second Statement:
W^2 > 1
The same that l W l > 1
w>1 or w<-1

so W > 1 is sufficient

I think that the answer is B

Could somebody correct me if I am wrong?


Last edited by dianapaolasanchez on Mon Jun 28, 2010 4:05 pm, edited 2 times in total.

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michael.g.pintar
 Post subject: Re: Is W greater than 1?
 Post Posted: Mon Jun 28, 2010 2:30 am 
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Course Students


Posts: 1
I believe you have answered your own question, but didn't look carefully enough.

Statement 2 states that w^2 > 1 which means w > 1 or w < -1. There is not enough information to determine whether it is positive or negative.

The two statements taken together result in -2 < w < -1 or w > 1, so the answer would be E, both statements taken together are not sufficient.
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RonPurewal
 Post subject: Re: Is W greater than 1?
 Post Posted: Thu Jul 08, 2010 8:27 am 
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ManhattanGMAT Staff


Posts: 6765
michael.g.pintar wrote:
I believe you have answered your own question, but didn't look carefully enough.

Statement 2 states that w^2 > 1 which means w > 1 or w < -1. There is not enough information to determine whether it is positive or negative.

The two statements taken together result in -2 < w < -1 or w > 1, so the answer would be E, both statements taken together are not sufficient.


yes.
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RonPurewal
 Post subject: Re: Is W greater than 1?
 Post Posted: Thu Jul 08, 2010 8:29 am 
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ManhattanGMAT Staff


Posts: 6765
the mistake is here:

dianapaolasanchez wrote:
Second Statement:
W^2 > 1
The same that l W l > 1
w>1 or w<-1

so W > 1 is sufficient


you can't do this -- you can't deduce sufficiency from half of a statement.
if the statement allows several different possibilities, you can't pick “sufficient” unless ALL of the possibilities agree. in this problem, this means that you have to get the same result from w > 1 as you get from w < -1. you can't just ignore the latter of these!
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vinversa
 Post subject: Re: Is W greater than 1?
 Post Posted: Sun Aug 01, 2010 7:00 am 
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Students


Posts: 30
http://www.postimage.org/image.php?v=aV9UBKr

Words in Picture form. OA = [E]

http://www.postimage.org/image.php?v=aV9UBKr
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RonPurewal
 Post subject: Re: Is W greater than 1?
 Post Posted: Thu Aug 05, 2010 9:24 am 
Offline
ManhattanGMAT Staff


Posts: 6765
vinversa wrote:
http://www.postimage.org/image.php?v=aV9UBKr

Words in Picture form. OA = [E]

http://www.postimage.org/image.php?v=aV9UBKr


very nicely done. thanks!
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