题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090053-95484.png)
答案
![]() | 0 | 1 | 2 | 3 | 5 |
P | ![]() | ![]() | ![]() | ![]() | ![]() |
解析
当ξ=0时表示没有巧合数,试验包含的所有事件是四个数在四个位置排列,共有
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090054-17987.png)
P
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090055-77729.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090053-55016.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090055-19637.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090054-48341.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090055-92750.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090054-37220.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090055-71750.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090054-65780.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090056-55201.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090054-98527.png)
核心考点
试题【数字1,2,3,4,5任意排成一列,如果数字k 恰好在第k个位置上,则称有一个巧合,则巧合数 的分布列为 .】;主要考察你对离散型随机变量及其分布列等知识点的理解。[详细]
举一反三
(1)求恰有两个岗位没有被选的概率;
(2)设选择A岗位的人数为
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090046-32328.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090046-32328.png)
甲:82 81 79 78 95 88 93 84 乙:92 95 80 75 83 80 90 85
(1)画出甲、乙两位学生成绩的茎叶图,指出学生乙成绩的中位数;
(2)现要从中选派一人参加数学竞赛,从平均状况和方差的角度考虑,你认为派哪位学生参加合适?请说明理由;
(3)若将频率视为概率,对学生甲在今后的三次数学竞赛成绩进行预测,记这三次成绩中高于80分的次数为
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090040-66646.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090040-66646.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191027/20191027090040-58201.png)