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# Standard Deviation

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Manager
Joined: 02 Apr 2006
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05 Nov 2007, 06:45
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Q. If a cetain sample of data has a mean of 20.0 and a standard deviation of 3.0, which of the following values is more than 2.5 standard deviations from the mean?

1) 12.0
2) 13.5
3) 17.0
4) 23.5
5) 26.5

Senior Manager
Joined: 19 Feb 2007
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05 Nov 2007, 06:48
2.5 SD = 2.5 * 3 = 7.5

more than 2.5 standard deviations from the mean is
either less than 20 - 7.5 = 12.5, or

greater than 20 + 7.5 = 27.5

So ans A
Manager
Joined: 02 Apr 2006
Posts: 93
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05 Nov 2007, 06:56
2.5 standard deviation from the mean
means
2.5 * SD??

Ah ah.. thank you.. so much..

sidbidus wrote:
2.5 SD = 2.5 * 3 = 7.5

more than 2.5 standard deviations from the mean is
either less than 20 - 7.5 = 12.5, or

greater than 20 + 7.5 = 27.5

So ans A
so...   [#permalink] 05 Nov 2007, 06:56
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