求一道GWD数学

小鱼good

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%
XDJM们，没看懂题意啊，帮忙解答一下吧

slickdeals

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 ?

The distribution is a symmetric about the mean.  68% between m+d and m-d.  Therefore the distribution of everything  >m+d and <m-d is 32%.  
The distribution less than m+d is 68% + 32%/2.    

tracyforever

求教！

cindytim

帮顶， 也想知道

切尔西

你的答案怎么四个红的，一个黑的，答案该是D的吧？