Kejadian A mempunyai peluang P(A) = 2/5 dan kejadian B mempunyai peluang P(B) = 1/2. Jika P(AuB) = 4/5, hitunglah : P(B'IA')

P(A n B) = P(A) + P(B) - P(A u B)
P(A n B) = 2/5 + 1/2 - 4/5
P(A n B) = 1/10

P(B | A) = P(A n B)/ P (A)
P(B | A) = 1/10 / 2/5
P(B | A) = 1/4

P(B' | A') = 1 - P(B | A) = 3/4