问题如下:
A stock obeying normal distribution has a mean return of 6% and a standard deviation of 18%. The probability for the stock's return to fall less than 4% is:
选项:
A.37.91%
B.45.62%
C.57.68%
解释:
B is correct. Firstly, standardize the original normal distribution:Z= (x-6%)/18%, so P(x <4%) = P( Z<-0.11).
Notice that N(-0.11) = 1- N(0.11). Based on the given table, N(0.11) = 0.5438, so N(-0.11) = 1-0.5438 = 0.4562 = 45.62%
, 老师您好,我的理解是P(Z<-0.1)即为 P(Z>0.11),为什么F(-0.11)=1-(F(0.11)呢,等式右边求出来的不就是我画的图上一大片区域的面积了吗(包括了中间的区域),谢谢