Question

求P(A∪B)=?已知P(A)=1/4,P(B|A)=1/3,P(A|B)=1/2,则P(A∪B)=?等于1/3对吗?

Answer 1

P(AB)=P(B|A)*P(A)=1/12 P(B)=P(AB)/P(A|B)=1/6

则P(A∪B)=P(A)+P(B)-P(AB)=1/4 + 1/6 - 1/12=1/3