1 . 对于一个随机试验,设
是样本空间,
是随机事件,
是样本点,则下列说法正确的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0047f659c182291c84c224df6b5e993f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/074c228ffc7b1e306f8410afe7bc4b5c.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
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解题方法
2 . 某种家用电器每台的销售利润与该电器的无故障时间
(单位:年)有关,若
,则销售利润为0元;若
,则销售利润为200元;若
,则销售利润为400元.设每台该种电器的无故障使用时间
,
,
这三种情况发生的概率分别为
,
,
,又知
,
为方程
的两根,且
.
(1)求
,
,
及
的值;
(2)记
表示销售两台这种家用电器的销售利润总和,求
的分布列及均值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b68df477b3ee45ac0f725db00d465a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdb63fe2175b6a19b3e16465baf7f301.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81f5f134de6306e097cb98cc66bd6bdd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cb924f709254c25d89ea96de86818c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdb63fe2175b6a19b3e16465baf7f301.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81f5f134de6306e097cb98cc66bd6bdd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cb924f709254c25d89ea96de86818c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797e67927616b141ed7c6b83f8b6f4fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c6048fc4daf0e7033000c9d8298e530.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd8935f02bb5855cf858306c3de1b5ae.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797e67927616b141ed7c6b83f8b6f4fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(2)记
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
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解题方法
3 . 某校组织的一次篮球定点投篮比赛,其中甲、乙、丙三人投篮命中率分别是
,
,三人各投一次,用
表示三人投篮命中的个数.
(1)求
的分布列及数学期望;
(2)在概率
中,若
的值最大,求实数
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e885b8b1915d48d5e55d826e3506a9c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
(2)在概率
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5e873ac240d885d83051f65b6be2f27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70ba16aac03850a376aa0f8328c9282b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
您最近一年使用:0次