If S is the sample space and , where A and B are two mutually exclusive events, then P(A) =

Question

Philoid · Accepted Answer

As , S = A ∪ B

∴ P(A ∪ B) = P(S) = 1

As A and B are mutually exclusive events.

∴ P(A ∪ B) = P(A) + P(B)

⇒ 1 = P(A) + 3P(A) [∵ P(A) = 1/3 P(B)]

⇒ 4P(A) = 1

∴ P(A) = 1/4

Our answer matches with option (a)

∴ Option (a) is the only correct choice