[求助]数学题求助

huangxiaoyan

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?

答案是75%.

喝咖啡的狼

 1 standard deviation = 0.3

10 - 0.3 < 9.9     9.9    9.9    10.0     10.2     10.2  < 10 + 0.3

so  6 / 8 = 75%

[此贴子已经被作者于2008-7-5 15:19:17编辑过]

huangxiaoyan

多谢