急问天山4-2

vancouverade

天山4－2

Q2:
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%

看了精华区的讨论连接,还是不明白啊,SIGH,哪位可否再指点下小弟,谢谢

ayang1017

题目说集合中都关于m点对称

然后说大于m-d小于m+d的为68％，那么两边小于m-d和大于m+d的应该分别是16％

所以小于m＋d的应该是大于m-d小于m+d的部分加上小于m-d＝84％

vancouverade

谢谢AYANG,太感谢了,