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[求助]一道Prep破解版的统计标准差的题目

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楼主
发表于 2008-11-15 20:36:00 | 只看该作者

[求助]一道Prep破解版的统计标准差的题目

110.
                
11364-!-item-!-187;#058&007646

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 deviation of 6 hours.  The number of hours that Pat, a resident of Town X, watched 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?

 

(A) 30

(B) 20

(C) 18

(D) 12

(E) 6

沙发
 楼主| 发表于 2008-11-15 21:17:00 | 只看该作者
好心人请帮忙解答一下吧
板凳
发表于 2008-11-17 16:09:00 | 只看该作者
同问!
地板
发表于 2008-11-17 16:16:00 | 只看该作者

看错了。。。是选D吗?

均数下1-2个标注差,就是低于6-12个小时。那就是9-15个小时,所以选D

5#
发表于 2008-11-17 17:47:00 | 只看该作者
the mean is 21, the standard deviation is 6

21-2*6 < Pat Hour < 21-1*6

               9<H<15

only the answer D is correct
6#
 楼主| 发表于 2008-11-19 21:32:00 | 只看该作者
 谢谢你的解答~~
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