解题方法
1 . 如果X,Y是两个离散型随机变量,
的所有可能取值为:
,则称
为
在
事件下的条件期望.已知甲每次投篮的命中率均为
,其中
,设随机变量
是甲第一次命中时的投篮次数,随机变量
是甲第二次命中时的投篮次数.
(1)若
,求
;
(2)已知
,求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fe1c31a81f198c443e71b83ca662939.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6a5dc4ce8f36f14dae312835cff836.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90a71f2ff30791e8b210727912600096.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20c11f6c800b8e0410674a0c6d307d26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a829fdd8ec0f3b7ede883cf2c3e53b.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f970f380a12c843bb4a74ff34a15b2ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f25b322e9f1f8a3aedd48a01e0af8290.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ed47b0d53fbc16d55c3921ab7b67d9c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de2fb32c2cb5bc9bbfb421f5747d2c27.png)
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