(2006)X的分布函數(shù)F(x),而F(x)=,則E(X)等于:()
A.0.7 B.0.75 C.0.6 D.0.8
A.0.4 B.0.6 C.0.5 D.0.3
A.P(B│A.=PB. B.P(A│)=PA. C.P(AB.=PA.PB. D.A,B互斥