Question

P(A) = 0.5
P(AUB) = 0.8
P(A/B) = 0.25

Qual a probabilidade de B?

Answer 1

$P(A/B)= \frac{P(A\cap B)}{P(B)} \\ 0,25.P(B)=P(A\cap B) \\ P(A\cup B)=P(A)+P(B)-P(A\cap B) \\ 0,8=0,5+P(B)-0,25P(B) \\ 0,3=0,75P(B) \\ P(B)=0,4$