If `A` and `B` are two events write the expression for the probability of occurrence of exactly one of two events.

Explanation

To find:


Probability that exactly one of the event occurs = `P \ `(` \ A` occurs and `B` does not occur) or `P \ `(` \ A `does not occur and `B` occurs)


`= P(AnnB’) + P(A’nnB)`


`= {P(A) -P(AnnB)} + {P(B) – P(AnnB)}`


`= P(A) + P(B)- P(AnnB)-P(AnnB)`


`= P(A) + P(B)- 2P(AnnB)`