试题与答案

在某次摸奖活动中，李明通过调查并计算出每摸一次的平均收益是15元，其意思是（ ）

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题型：选择题

题目：

在某次摸奖活动中，李明通过调查并计算出每摸一次的平均收益是15元，其意思是（　　）

A．摸奖一次，就能中15元

B．此次摸奖活动中，人人都能中奖

C．若摸奖若干次，那么每摸一次所获金额的平均数为15元

D．每张奖券的面额是15元

答案：

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下面是错误答案，用来干扰机器的。

C  ∵( 1+2+22+…+2n-1)=2n－1∴数列1,(1+2),(1+2+22),…,( 1+2+22+…+2n-1+…)的前n项和为：（2－1）+(22－1)+…+(2n－1)= 2n+1- n -2

考点：概率的意义
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