从2020年开始,学习强国开通了一项“争上游答题”栏目,其规则是在一天内参与答题活动,仅前两局比赛有积分,首局获胜积3分,次局获胜积2分,失败均得1分.若甲每局比赛获胜的概率为
,每局比赛相互独立.记甲某天参加答题活动(参与2局比赛以上)的得分为
,则得分的数学期望![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ae496f35db5bbc578a32d893e6e01a.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ae496f35db5bbc578a32d893e6e01a.png)
2021·江西赣州·二模 查看更多[3]
更新时间:2021-05-10 21:40:33
|
相似题推荐
填空题-双空题
|
较易
(0.85)
解题方法
【推荐1】袋子中有除颜色外形状完全相同的3个红球,2个白球.每次拿一个球,不放回,共拿两次.设拿出的白球个数为
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61d4a06e746468c4f1ccbd124d9b9142.png)
________ ,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75c307c420a3546176fbe7fc250252b2.png)
________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b734e8f1546481e3eb4976008a045de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61d4a06e746468c4f1ccbd124d9b9142.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75c307c420a3546176fbe7fc250252b2.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】离散型随机变量
的概率分布规律为
,
,其中
是常数,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/899002c3e526cf9a221b9ed05ede7263.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33d440101f11c0918c9ec59c70c1a29a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f954c4e0e662b38d64e8518ce9d9c79c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/899002c3e526cf9a221b9ed05ede7263.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】对于随机变量X,它的数学期望
和方差
,下列所有正确的序号是______ .
①
是反映随机变量的平均取值; ②
越小,说明X越集中于
;
③
; ④
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bf3baba074e8aeb6f3ea117865bbd1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90a0722562d03a0a55a6c63e5d4cc338.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bf3baba074e8aeb6f3ea117865bbd1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90a0722562d03a0a55a6c63e5d4cc338.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bf3baba074e8aeb6f3ea117865bbd1b.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6b381d5ff1ed465f8fef96f75761e17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ac91813b4adeb949a89b1f0d264bd36.png)
您最近一年使用:0次
填空题-单空题
|
较易
(0.85)
名校
【推荐2】一个盒子里有1个红球和2个绿球,每次拿一个,不放回,拿出红球即停,设拿出绿球的个数为
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac87b4bd71432d757c7b78bbd6b2dcfd.png)
__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac87b4bd71432d757c7b78bbd6b2dcfd.png)
您最近一年使用:0次