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Standard deviation

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Standard deviation

by michaelisk » Thu Aug 18, 2011 1:06 pm
The residents of town x participated in a survey to determine the number of hours per week each resident spent watching television. The distribution of the results of the survey had a mean of 21 hours and a standard distribution of 6 hours. The number of hours that Pat, a resident of town X, watch television last week was between 1 and 2 standard deviations below the mean. Which of the following could be the number of hours that pat watched television last week?

30
20
18
12
6
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by catseye » Thu Aug 18, 2011 1:20 pm
Two Standard Deviation (SD) rules:

1 SD. below mean =Mean-1*SD
2 SD. Below mean=Mean-2*SD.
Solution to the problem:
Given,
Mean =21; and SD=6
1 SD. Below mean =21-1*6=15
2 SD below mean =21-2*6=9

The value between 15 and 9 is 12.

[spoiler]Answer: 12[/spoiler]
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