题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101505-20196.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101505-35969.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101505-36792.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101505-97720.png)
A.![]() | B.![]() | C.![]() | D.![]() |
答案
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101505-20196.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101505-35969.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101505-36792.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101507-11808.png)
核心考点
举一反三
A.![]() | B.![]() | C.![]() | D.![]() |
A.随机事件 | B.必然事件 | C.不可能事件 | D.无法确定 |
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101440-20712.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101440-84715.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101441-21275.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101441-21597.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101441-20796.png)
某校举行环保知识大奖赛,比赛分初赛和决赛两部分,初赛采用选一题答一题的方式进行。每位选手最多有5次答题机会。选手累计答对3题或答错三题终止初赛的比赛。答对三题直接进入决赛,答错3题则被淘汰。已知选手甲连续两次答错的概率为
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101433-30842.png)
(1)求选手甲回答一个问题的正确率;
(2)求选手甲进入决赛的概率;
(3)设选手甲在初赛中答题个数为X,试写出X的分布列,并求甲在初赛中平均答题个数。
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101422-83898.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101422-37245.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101422-63560.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101423-20100.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027101423-24578.png)