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# GMAT Prep- Standard Deviation Problem

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Intern
Joined: 24 May 2008
Posts: 32
GMAT Prep- Standard Deviation Problem [#permalink]

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20 Jun 2008, 21:19
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Can some one explain the below problem? Thanks!
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Mahesh Vollala

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Joined: 21 Mar 2008
Posts: 240
Re: GMAT Prep- Standard Deviation Problem [#permalink]

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20 Jun 2008, 21:46
Mean = 21
Sd = 6

1 Sd below the mean is 21-6 = 15
2 Sd below the mean is 21-12 = 9

So the only choice is 12 between 15 and 9
Re: GMAT Prep- Standard Deviation Problem   [#permalink] 20 Jun 2008, 21:46
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