# Question: Let A1 A2 An be arbitrary events

Let A1, A2, . . . ,An be arbitrary events, and define Ck = {at least k of the Ai occur}. Show that

Let X denote the number of the Ai that occur. Show that both sides of the preceding equation are equal to E[X].

Let X denote the number of the Ai that occur. Show that both sides of the preceding equation are equal to E[X].

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