题目
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答案
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解析
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003314-12102.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003313-12335.png)
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ξ | ![]() | ![]() | ![]() | 1 |
P | ![]() | ![]() | ![]() | ![]() |
所以Eξ=
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003315-82193.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003314-43442.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003315-82193.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003315-50980.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003315-82193.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003315-94664.png)
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核心考点
试题【. 设l为平面上过点(0,l)的直线,l的斜率等可能地取、、、0、、、,用ξ表示坐标原点到直线l的距离,则随机变量ξ的数学期望Eξ=_________.】;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
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003307-66606.png)
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元.两种产品生产的质量相互独立.
(Ⅰ)设生产
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003239-61207.png)
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(Ⅱ)求生产
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![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003241-14434.png)
安排四个大学生到A、B、C三个学校支教,设每个大学生去任何一个学校是等可能的.
(1)求四个大学生中恰有两人去A校支教的概率.
(2)设有大学生去支教的学校的个数为
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003227-96270.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191030/20191030003227-96270.png)
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