若随机变量X的分布列为则X的数学期望为______________ .
X | -1 | 2 | 4 | 5 |
P | 0.2 | 0.35 | 0.25 | 0.2 |
更新时间:2023-03-26 13:02:33
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【知识点】 求离散型随机变量的均值解读
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填空题-概念填空
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容易
(0.94)
【推荐1】均值的性质
若
,其中a,b为常数,X是随机变量,
(1)Y也是随机变量.
(2)![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3909577cb9dde1054ab8e8c94bd17169.png)
_________ .
若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f9c2a44bf6cf4f7f0f332b8fdeb9e89.png)
(1)Y也是随机变量.
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3909577cb9dde1054ab8e8c94bd17169.png)
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填空题-双空题
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容易
(0.94)
【推荐2】已知离散型随机变量
的分布列为
则变量
的数学期望![](https://staticzujuan.xkw.com/quesimg/Upload/formula/223770da09feb2fc824764188e924d7e.png)
_________ ,方差![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd353481279871d4c18541586c319c8d.png)
____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![]() | 0 | 1 | 2 |
![]() | ![]() | ![]() | ![]() |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/223770da09feb2fc824764188e924d7e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd353481279871d4c18541586c319c8d.png)
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