Final answer:
To find P(A|B), divide the probability of A and B occurring by the probability of B occurring.
Step-by-step explanation:
To find P(A|B), we can use the formula P(A|B) = P(A AND B) / P(B). Given that P(B) = 0.5 and P(A ∩ B) = 0.4, we can substitute these values into the formula to get P(A|B) = 0.4 / 0.5 = 0.8. Therefore, the probability of event A occurring given that event B has occurred is 0.8.