题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195421-22759.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195421-43329.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195421-76932.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195421-43329.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195421-98290.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195422-96850.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195422-12891.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195422-80966.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195422-70115.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195423-95498.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195423-24912.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195423-42414.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195423-44824.png)
答案
解析
由图象可知,此正态分布为标准正态分布,其函数的解析式为
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195424-20740.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195424-31346.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195424-31346.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195424-31346.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195424-29270.png)
又由
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195424-20740.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195424-59312.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195424-22450.png)
由图象知
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195425-77904.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195425-64358.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195425-63820.png)
故正确答案为
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195425-47594.png)
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195412-44790.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195413-78596.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195413-20351.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195413-77696.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195413-48355.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195414-60551.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195414-71268.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195414-58246.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195414-93525.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195414-65171.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195415-33007.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195415-89199.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195406-40576.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195406-79267.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195406-66386.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195406-40576.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195406-68534.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195407-18564.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195407-14707.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195407-87670.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195407-45139.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195408-84830.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195408-72955.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195408-79312.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195408-77663.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195409-52938.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195357-91631.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195358-88934.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195358-58247.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195358-64976.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195349-14506.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195349-12965.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195349-45673.gif)
(1)求乙、丙两人各自回答这道题对的概率;
(2)用
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195350-64442.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195350-64442.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191026/20191026195350-51343.gif)
(本小题满分12分)
某日用品按行业质量标准分成五个等级,等级系数X依次为1,2,3,4,5.现从一批该日用品中随机抽取20件,对其等级系数进行统计分析,得到频率分布表如下:
(1) 若所抽取的20件日用品中,等级系数为4的恰有3件,等级系数为5的恰有2件,求a、b、c的值;
(11)在(1)的条件下,将等级系数为4的3件日用品记为x1, x2, x3,等级系数为5的2件日用品记为y1,y2,现从x1, x2, x3, y1, y2,这5件日用品中任取两件(假定每件日用品被取出的可能性相同),写出所有可能的结果,并求这两件日用品的等级系数恰好相等的概率.
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