Question

已知事件A,B有概率P(A)=0.4P(B)=0.5,条件概率P(B拔|A)=0.3,

Answer 1

P(B|A)=P(A∩B)/P(A)

P(A∩B) = P(A).P(B|A)

=0.4(0.3)

=0.12

P(A∪B)=P(A)+P(B)-P(A∩B) =0.4+0.5-0.12=0.78