解题方法
1 . 已知随机变量
满足
,
,则( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2cc3e078cd3f374cfb9edbe26461ebf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e50889dedb04095de218ff3a6e1dddc.png)
A.![]() ![]() | B.![]() ![]() |
C.![]() ![]() | D.![]() ![]() |
您最近一年使用:0次
名校
解题方法
2 .
年
月
日,国务院办公厅印发《关于进一步减轻义务教育阶段学生作业负担和校外培训负担的意见》.“双减”政策指出,要全面压减作业总量和时长,某校在“双减”前学生完成作业时长为随机变量
,
的期望为
,标准差为
,在“双减”后,该校学生完成作业的时长
,
的期望为
,标准差为
,则( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/151e5633a5d0cc30b254167e3dda5803.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b06e95b57b7a81cd81d05557a11fa92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49e60fbe6820130fb20abc555a94b5ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e87ff70b37d7cfb3aae5438c8eddf945.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5c1116ce7f5a1a7b57517276d5092fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad481cbfb67ac9cdbc0537f3de23b022.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5873c01192b7d33b7483f444f90b5b0.png)
A.![]() ![]() | B.![]() ![]() |
C.![]() ![]() | D.![]() ![]() |
您最近一年使用:0次
2021-12-01更新
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628次组卷
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6卷引用:山西省临汾市尧都区山西师范大学实验中学2021-2022学年高二下学期第一次月考数学试题