设X~N(3,4),试求(1)P(5<X<9);(2)P(X>7).(已知ф(1)=0.8423,ф(2)=0.9772,ф(3)=0.998

问题描述:

设X~N(3,4),试求(1)P(5<X<9);(2)P(X>7).(已知ф(1)=0.8423,ф(2)=0.9772,ф(3)=0.998

(1)P(5<X<9)
=P(X