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

完全没有思路哦，请指教。

d takes 68%

so the M to D takes 34%

the percent less than M should be 50%

so the M+D= 84%

you can draw it.