Let A and B be two events such that P(B∣A)=25P(B|A)=\dfrac25P(B∣A)=52, P(A∣B)=17P(A|B)=\dfrac17P(A∣B)=71 and P(A∩B)=19P(A\cap B)=\dfrac19P(A∩B)=91. Consider
(S1) P(A′∪B)=56P(A'\cup B)=\dfrac56P(A′∪B)=65,
(S2) P(A′∩B′)=118P(A'\cap B')=\dfrac1{18}P(A′∩B′)=181
Then
Official answer: A
Probabilities. P(A)=518P(A)=\frac5{18}P(A)=185, P(B)=79P(B)=\frac79P(B)=97.
(S1). 1−P(A∩B′)=1−318=561-P(A\cap B')=1-\frac3{18}=\frac561−P(A∩B′)=1−183=65. (S2). 1−P(A∪B)=1−1718=1181-P(A\cup B)=1-\frac{17}{18}=\frac1{18}1−P(A∪B)=1−1817=181. Both true.
(A)