OG数学里的EXAMPLE4.2.9没看明白是什么意思，求好心人帮忙^_^！

tina801103

Example 4.2.9: Six hundred applicants for several post office jobs were rated on a
scale from 1 to 50 points. The ratings had a mean of 32.5 points and a standard deviation
of 7.1 points. How many standard deviations above or below the mean is a rating
of 48 points? A rating of 30 points? A rating of 20 points?



题目和解题思路都没有看明白，不知道为什么要这样算。求助求助！！！感谢感谢！！！

竹林中人

期望是32.5，标准差是7.1，那么48对应着期望以上多少个标准差，应该是（48-32.5）/7.1吧，其他的依此类推。

tina801103

竹林中人 发表于 2014-5-9 21:59
期望是32.5，标准差是7.1，那么48对应着期望以上多少个标准差，应该是（48-32.5）/7.1吧，其他的依此类推。 ...

谢谢版主！！！