Given, 2P(B) = P(A) = 6/13
2P(B) = 6/13; P(B) = 3/13 again, P(A) = 6/13
According to question,
P(A/B) = 1/3; P(A ∩ B)/P(B) = 1/3; P(A ∩ B)/(3/13) = 1/3
P(A ∩ B) = (1/3) x (3/13)
P(A ∩ B) = 1/3
P(A ∪ B) = p(A) + P(B) - P(A ∩B)
= (6/13) + (3/13) - (1/13)
= (6 + 3)/13 - (1/13)
= (9/13) - (1/13)
= 8/3