Let A and B be two mutually exclusive events of a random experiment such that P(not A) = 0.65 and P(A or B) = 0.65, find P(B).

Given : A and B are mutually exclusive events


P(not A) = P() = 0.65 , P(A or B) = 0.65


To find : P(B)


Formula used : P(A) = 1 – P()


P(A or B) = P(A) + P(B) - P(A and B)


For mutually exclusive events A and B, P(A and B) = 0


P(A) = 1 – P(not A)


P(A) = 1 – 0.65


P(A) = 0.35


Substituting in the above formula we get,


0.65 = 0.35 + P(B)


P(B) = 0.65 – 0.35


P(B) = 0.30


P(B) = 0.30


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