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标题: 求教一道prep数学 [打印本页]

作者: lingqiang    时间: 2011-10-28 18:04
标题: 求教一道prep数学
The arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 1.5, respectively. What value is exactly 2 standard deviations less than the mean?



A 10.5

B 11.0

C 11.5

D 12.0

E 12.5


求解释一下怎么算

作者: lingqiang    时间: 2011-10-28 18:05
额、、、、、刚发完贴又懂了。。。。
作者: copyrightice    时间: 2011-10-28 18:13
13.5-1.5*2=10.5




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