题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001754-16982.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001754-16982.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001754-61608.png)
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001754-94521.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001755-29793.png)
核心考点
试题【有一批产品,其中有12件正品和4件次品,从中任取3件,若表示取到次品的个数,则E= .】;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
甲乙两名射手互不影响地进行射击训练,根据以往的数据统计,他们设计成绩的分布列如下:
射手甲 | 射手乙 | ||||||
环数 | 8 | 9 | 10 | 环数 | 8 | 9 | 10 |
概率 | ![]() | ![]() | ![]() | 概率 | ![]() | ![]() | ![]() |
(Ⅱ)若两个射手各射击1次,记所得的环数之和为
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001733-31026.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001733-31026.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001717-80359.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001704-86234.png)
A.0.4 | B.1.2 | C.1.6 | D.2 |
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001704-25912.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030001649-63060.png)