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# Standard Deviation

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VP
Joined: 18 May 2008
Posts: 1258

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17 Mar 2009, 01:47
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

I have a querry related to standard deviation.
I read sum where that " Standard deviation of a set is always non-negative and equals 0 only if all members of the set are the same". But wht abt the standard deviation in the following set:

(2,4,6,8,10,12)
CEO
Joined: 17 Nov 2007
Posts: 3583
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40

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17 Mar 2009, 03:38
$$SD = \sqrt{\frac{(2-7)^2+(4-7)^2+(6-7)^2+(8-7)^2+(10-7)^2+(12-7)^2}{6}} = \sqrt{\frac{5^2+3^2+1^2+1^2+3^2+5^2}{6}} > 0$$

Think about SD as average of |x-xav|.
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Re: Standard Deviation   [#permalink] 17 Mar 2009, 03:38
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# Standard Deviation

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