Question

P(A)=0.7;P(AB)=0.3;P(非A非B）=0.2；怎么求P（B）?

Answer 1

P(非A非B）=（1-P(A)）（1-P(B)）=1-P(A)-P(B)+P(AB)=1-0.7-P(B)+0.3=0.2

解得P(B)=0.4