4封信随机投入A,B,C三个空邮箱,则邮箱A的信件数X的数学期望![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac87b4bd71432d757c7b78bbd6b2dcfd.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac87b4bd71432d757c7b78bbd6b2dcfd.png)
更新时间:2023-07-10 11:52:08
|
相似题推荐
填空题-双空题
|
较易
(0.85)
解题方法
【推荐1】同时抛掷两枚质地均匀的硬币,当至少有一枚硬币正面向上时,就说这次试验成功,设在2次试验中成功次数为
,设![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac87b4bd71432d757c7b78bbd6b2dcfd.png)
__ ,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc23dc1709498e8920d7d243213190b2.png)
__ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac87b4bd71432d757c7b78bbd6b2dcfd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc23dc1709498e8920d7d243213190b2.png)
您最近一年使用:0次
填空题-单空题
|
较易
(0.85)
解题方法
【推荐2】假设苏州肯帝亚球从在某赛季的任一场比赛中输球的概率都等于
,其中
,且各场比赛互不影响.令
表示连续9场比赛中出现输球的场数,且令
代表9场比赛中恰有
场出现输球的概率
.已知
,则该球队在这连续9场比赛中出现输球场数的期望为___________ .
![](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/dbe0f61ec213734b7ae080719fa5cdd3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef133b0fd53a48310a82c18729575abd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44f6b88c72bda9c1f2a5bc58d9b2b071.png)
您最近一年使用:0次
填空题-单空题
|
较易
(0.85)
解题方法
【推荐1】一个箱子中装有形状完全相同的5个白球和
个黑球,现从中有放回的摸取4次,每次都是随机摸取一球,设摸得白球个数为X,若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac87b4bd71432d757c7b78bbd6b2dcfd.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/098afe75dd67aa4c2d1f0b6616c4c1ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d97daa0796af9cbbe34e8eec38d0f06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac87b4bd71432d757c7b78bbd6b2dcfd.png)
您最近一年使用:0次
填空题-双空题
|
较易
(0.85)
解题方法
【推荐2】设随机变量
,
,若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e60ff3d4d0abd4a75cc521c0267f92e.png)
__________ ,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25da290affab7bc1a849c4be4d45879f.png)
____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cab090bf8d7ac3466b2d38a2e78ed5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4c5525bafc848d4b7807a395a9b9d47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d8342c14a5d5b671e1ab46886c1811b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e60ff3d4d0abd4a75cc521c0267f92e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25da290affab7bc1a849c4be4d45879f.png)
您最近一年使用:0次