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SD and Range

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by sampath » Fri Aug 12, 2011 12:32 pm
Is the standard deviation of a certain set greater than
15,000?
1). The range of the set is 25,000
2). The mean of the set is 150,000

[spoiler]I think the answer should be E as from Stmt 1, since range is always greater than or equal to the SD, the stmt doesnt yield any specific value for SD which could either be less than or greater than 15000.
The second stmt also seems insuff. Together also, we can't calculate the SD.[/spoiler]
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Source: — Data Sufficiency |

by bblast » Fri Aug 12, 2011 10:14 pm
hi, I see u posted 2 question testing the same concept

The answer to both will be E as we need to know the number of elements and more importantly we need to calculate the "distance" of each element of the set from the mean for the SD. So the range is useless here. The mean can be useful but only if we know the individual elements.
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