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标题: 请教大牛GMATPREP数学解题思路!!! [打印本页]

作者: mendly    时间: 2006-11-4 14:59
标题: 请教大牛GMATPREP数学解题思路!!!

9.4 9.9 9.9 9.9 10.0 10.2 10.2 10.5
                

The mean and the standard deviation of the 8 numbers shown are 10.0 and 0.3,respectively, what percent of the 8 numbers are within 1 standard deviation of the mean?

Ans:75%

烦请大牛解释一下,多谢了!!!


作者: mendly    时间: 2006-11-4 15:10

9.4 9.9 9.9 9.9 10.0 10.2 10.2 10.5
                

The mean and the standard deviation of the 8 numbers shown are 10.0 and 0.3,respectively, what percent of the 8 numbers are within 1 standard deviation of the mean?
                

Ans:75%

烦请大牛解释一下,多谢了!!!


作者: xiaowan    时间: 2006-11-4 16:33
呵呵。。。题目问的是这8个数中在均值一倍标准差范围内的数的比例,也就是在9.7--10.3范围内数的比例咯,有6个数满足,这样6/8=百分之75啦




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