Question

X³~N(1,7²),则P(1<X<2)等于？

Answer 1

问：X³~N(1,7²),则P(1

答：随机变量X服从正态分布N(1,4)即N(1,22)那么P(-2amp;xamp;2)=Φ[(2-1)/2] - Φ[(-2-1)/2]=Φ(0.5) -Φ(-1.5)=Φ(0.5) - [1-Φ(1.5)]=Φ(0.5) +Φ(1.5) -1=0.6915+0.93319 -1=0.62469