Suppose E1, E2, and E3 are any events in a given experiment. Use Theorem 2 on page 450 to help you derive the probability that E1 or E2 or E3 occurs. That is, derived Prob(E1 or E2 or E3).

Theorem 2: The General Sum Rule:If E1 and E2 are any events in a given experiment, then the probability that E1 and E2 occurs is given byProb(E1 or E2) = Prob(E1) + Prob(E2) - Prob(E1 and E2)If E1 and E2 are disjoint, then E1 n E2 = 0 , so Prob(E1 and E2) = 0.