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标题: 请牛牛们帮我解答，prep1-106数学 [打印本页]

作者: lezifanwen 时间: 2008-6-20 21:09
标题: 请牛牛们帮我解答，prep1-106数学

106 If a certain sample fo data has a mean of 20.0and a standard deviation of 3.0, which of the following values is more 2.5 standard deviations from the mean?

A 12.0

B 13.5

C 17.0

D 23.5

E 26.5

答案是A

请牛牛们帮我解答，谢谢了！

作者: mymengming 时间: 2008-6-21 00:35
你给的题目有问题啊，

If a certain 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?

(A) 12.0

(B) 13.5

(D) 23.5

(E) 26.5

意思是问哪个是在2个半标准差外的，20+/-2.5×3
只有12符合

作者: lezifanwen 时间: 2008-6-21 14:59
太感谢牛牛了！

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