问题如下:
A fund manager finds that the return of funds in the market are normally distributed having a mean of $170,000 and a standard deviation of $25,000. The percent of stock incomes greater than $245,000 is closest to:
选项:
A.0.50%.
B.2.28%.
C.0.13%.
解释:
C is correct.
Z=(245000 - 170000)/25000=F(3)
1 - F(3) = 1 - 0.9987 = 0.0013.
完全不知道为什么这么算了,不是已经是正态分布了么,怎么还需要转换?F(3)代表什么?