GMAT PREP S.D

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by Night reader » Sat Feb 12, 2011 9:22 pm
btgyes wrote:[spoiler]E is ans.

explain ...[/spoiler]
The only way the standard deviation (d) is minimized is when d=0; d can't be less than 0!
therefore the only way when d is 0, all our values are equal and the average is the 100% descriptive central tendency measure for the data set. Thus, we must imply that the values a(n=1...100) are not equal initially.
So, when we pick E, we assume that picking two equal values will make our average to be close to the value 6 itself. While we pick 6, we can't pick 0, as there's opposite effect on our value set dispersion then.
this is a pure concept test.
hope this helps.