题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193438-21311.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193438-61818.gif)
(Ⅰ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193438-61818.gif)
(Ⅱ)若
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193439-98380.gif)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193439-63162.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193439-70609.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193439-40653.gif)
所
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193440-30877.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193440-67457.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193440-84537.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193440-93765.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193439-63162.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193439-70609.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193439-40653.gif)
………………1分
(Ⅰ)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193438-61818.gif)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193441-35878.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193441-36097.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193441-23212.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193441-34622.gif)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193442-81079.gif)
![]() | ![]() | ![]() | ![]() | ![]() |
![]() | ![]() | ![]() | ![]() | ![]() |
(Ⅱ)因为
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193444-91716.gif)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193444-96277.gif)
…………………6分
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193444-21271.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193445-38503.gif)
解得
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193445-37061.gif)
所以a的取值范围是
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193445-71267.gif)
解析
核心考点
试题【 (本题10分)甲、乙、丙三名射击运动员射中目标的概率分别为(0<a<1),三各射击一次,击中目标的次数记为。(Ⅰ)求的分布列;(Ⅱ)若的值最大,求实数a的取值】;主要考察你对随机事件的概率等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193433-25324.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193433-91921.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193434-93945.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193427-17409.gif)
![]() | 0 | 1 | ![]() |
![]() | ![]() | ![]() | ![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193429-90332.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193429-98391.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193429-36169.gif)
有三张形状、大小、质地完全一致的卡片,在每张卡片上分别写上0,1,2,现从中任意抽取一张,将其上的数字记作
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193421-55590.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193422-86510.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193422-82931.gif)
(Ⅰ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193422-66229.gif)
(Ⅱ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193422-66229.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193422-66229.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193414-96761.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193414-30802.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193414-54708.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193415-51967.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193415-54888.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193415-54068.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193415-14031.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193415-54068.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193416-81330.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193416-91189.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193416-24976.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193416-19296.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193417-52871.gif)
若有七组数据列表如下:
x | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
y | 4 | 6 | 5 | 6.2 | 8 | 7.1 | 8.6 |
(Ⅰ)求上表中前三组数据的回归直线方程;
(Ⅱ)若
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193417-78711.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193417-12175.gif)
检测部门决定对某市学校教室的
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193408-45787.gif)
每间教室的检测方式如下:分别在同一天的上、下午各进行一次检测,若两次检测中有C级或两次都是B级,则该教室的空气质量不合格. 设各教室的空气质量相互独立,且每次检测的结果也相互独立. 根据多次抽检结果,一间教室一次检测空气质量为A、B、C三级的频率依次为
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193408-65145.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193409-20751.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026193409-20751.gif)
(1) 在该市的教室中任取一间,估计该间教室空气质量合格的概率;
(2) 如果对该市某中学的4间教室进行检测,记在上午检测空气质量为A级的教室间数为X,并以空气质量为A级的频率作为空气质量为A级的概率,求X的分布列及期望值.
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