题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233036-38785.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233036-81269.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233036-84357.png)
解析
试题分析::∵随机变量ξ服从二项分布,且
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233036-34128.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233036-81269.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233037-67944.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233037-67944.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233036-84357.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233036-84357.png)
核心考点
试题【设随机变量,则 .】;主要考察你对离散型随机变量均值与方差等知识点的理解。[详细]
举一反三
(I)连续达到60秒可转动转盘(转盘为八等分圆盘)一次进行抽奖,达到90秒可转两次,达到120秒可转三次(奖金累加).
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233026-46065.png)
(2)转盘指针落在I、II、III区依次为一等奖(500元)、二等奖(200元)、三等奖(100元),落在其它区域不奖励.
(3)演唱时间从开始到三位评委中至少1人呜啰为止,现有一演唱者演唱时间为100秒.
①求此人中一等奖的概率;
②设此人所得奖金为
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233026-37464.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233026-37464.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233026-55403.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233020-49342.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191029/20191029233020-84766.png)