Question

已知P(A)=0.7,P(A-B)=0.5,求P(B|A)

Answer 1

P(A-B)=P(A)-P(AB)=0.5，
所以 P(AB)=P(A)-0.5=0.2，
因此 P(B|A)=P(AB)/P(A)=0.2/0.7=2/7。

Answer 2

最后答案0.5!因为:P(A)=0.7, P(A-B)=0.5所以:P=0.5/(A-B),导出,0.7/A=0.5/(A-B).最后得出,A=3.5B。将:P=0.7/A,和A=3.5B,代入,P(A*B的并)=最后得出0.5!...

Answer 3

P(A-B)=0.5

根据定义 P(A-B) =P(A)-P(A∩B)

P(A)-P(A∩B)=0.5

带入P(A)=0.7

0.7-P(A∩B)=0.5

P(A∩B)=0.2

根据定义 P(B|A) =P(A∩B)/P(A)

P(B|A) 

=P(A∩B)/P(A)

=0.2/0.7

=2/7

得出结果·

P(B|A) =2/7

Answer 4

p(A-B)=p(A)-p(AB)=0.5,所以p(AB)=0.7-0.5=0.2 。p(B|A)=p(AB)/p(A)=0.2/0.7=2/7

Answer 5

结果1
P（A∪B)=P(A)+P(B)-P(AB)=1.2-P(AB) ∈[0,1]又P(AB)∈[0,1] 所以P(AB)∈[0.2,1] P(AB)的最小值是0.2