問題詳情

Problem 17. (2.5 %) N people put their hats in a closet at the start of a party,where each hat is uniquely identifed. At the end of the party each person ran-domly selects a hat from the closet. Suppose N is a Poisson random variablewith parameter

. If X is the number of people who pick their own hats, thenE[X] is equal to
(A)


(B)


(C)


(D)1

參考答案

答案：[無官方正解]
難度：計算中-1
書單：沒有書單，新增