请教一道GWD数学题 - 标准方差

weiwei_zhwq

A certain characteristic in a large population has a distribution that is symmetric about the mean m. If 68 percent of the distribution lies within one standard deviation d of the mean,
what percent of the distribution is less than m + d ?

A. 16%
B. 32%
C. 48%
D. 84%
E. 92%

没看懂题目   ...请教思路和步骤~~谢谢~~

zincgirl

在网上看到了答案

某一特性在大人口基数的条件下具有关于平均值M对称的分布，如果68%分布于平均值的一个标准偏差D内，那么分布于小于M+D的概率是多少？

a distribution that is symmetric about the mean M: 50% is less than M
68% of the distribution lies within one standard deviation D of the mean: 34% is between M - D, and 34% is between M and M + D
so 50% + 34% = 84% is less than M + D.唐卫公 | 十六级
应该是对的， 如果后来人也看了这道题，可以参考一下～