请教大牛ＧＭＡＴＰＲＥＰ数学解题思路！！！

mendly

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！！！

mendly

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！！！

xiaowan

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