Question

Find the missing probability. P(A)=2/5,P(B|A)=920,P(A∩B)

Answer 1

I think you meant P(B | A) = 9/20.

By definition of conditional probability,

P(B | A) = P(A ∩ B) / P(A)

so that

P(A ∩ B) = P(A) × P(B | A) = 2/5 × 9/20 = 18/100 = 9/50