1 . 某校对高三部分学生的数学质检成绩做相应分析.
(1)按一定比例分层抽样抽取了20名学生的数学成绩,并用茎叶图记录,但部分数据不小心丢失了.已知数学成绩在[70,90)的频率是0.2,请补全下表并绘制相应频率分布直方图.
![](https://img.xkw.com/dksih/QBM/2016/10/16/1573072174120960/1573072180191232/STEM/dc61bf4c92a6423083614bd5615fd08d.png)
(2)为考查学生的物理成绩与数学成绩是否有关系,抽取了部分同学的数学成绩与物理成绩进行比较,得到统计数据如下:
能够有多大的把握认为物理成绩优秀与数学成绩优秀有关系?
附:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf9db39550a308daae60f22caf69140a.png)
(1)按一定比例分层抽样抽取了20名学生的数学成绩,并用茎叶图记录,但部分数据不小心丢失了.已知数学成绩在[70,90)的频率是0.2,请补全下表并绘制相应频率分布直方图.
![](https://img.xkw.com/dksih/QBM/2016/10/16/1573072174120960/1573072180191232/STEM/dc61bf4c92a6423083614bd5615fd08d.png)
(2)为考查学生的物理成绩与数学成绩是否有关系,抽取了部分同学的数学成绩与物理成绩进行比较,得到统计数据如下:
物理成绩优秀 | 物理成绩一般 | 合计 | |
数学成绩优秀 | 15 | 3 | 18 |
数学成绩一般 | 5 | 17 | 22 |
合计 | 20 | 20 | 40 |
能够有多大的把握认为物理成绩优秀与数学成绩优秀有关系?
附:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf9db39550a308daae60f22caf69140a.png)
P(K2≥K0) | 0.05 | 0.01 | 0.005 | 0.001 |
![]() | 3.841 | 6.635 | 7.879 | 10.828 |
您最近一年使用:0次
解题方法
2 . 某校学生利用元旦节进行社会实践,在
岁的人群随机抽取
人,进行了一次“是否已养成垃圾分类习惯”的调查,得到如下统计表和各年龄段人数频率分布直方图:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/10/2230fb44-76f2-46d7-b9b2-408572ee2498.png?resizew=291)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/10/5c9035ee-3189-43d4-ab6c-18a20573a6ca.png?resizew=425)
(1)补全频率分布直方图并求
、
、
的值;
(2)从
岁年龄段的“已养成垃圾分类习惯的人”中采用分层抽样法抽取
人参加垃圾分类宣讲活动,其中选取
人作为领队,求选取的
名领队年龄都在
岁的概率.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15f216d9300fc6a66a5fb3a4a3c01112.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/10/2230fb44-76f2-46d7-b9b2-408572ee2498.png?resizew=291)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/10/5c9035ee-3189-43d4-ab6c-18a20573a6ca.png?resizew=425)
(1)补全频率分布直方图并求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
(2)从
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b60353a13a691a89e77a45d0e4bd072.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8c4c029e552954bd493b49aeab82d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74fec878623fb050bf545f23504201e7.png)
您最近一年使用:0次
3 . 如图所示,在四棱锥
中,
平面
,又
,
,且
.
![](https://img.xkw.com/dksih/QBM/2016/5/20/1572643202678784/1572643208347648/STEM/f126915e67d24850b4717b1d83fc697d.png)
(1)在网格中画出四棱准
的正视图;
(2)求证:平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
平面
;
(3)在棱
上是否存在一点
,使得
平面
,若存在,求
的值. 若不存在,请说明理由
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6153163fecdf3f410411048428ccaef5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e458f4503e211b542f6f30c8a34eaca5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34e0a957a55460c72673c0f2ee90dbb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63ab4d12ad313f0087c6e32d5118ba28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce2152d060ef82e9e60f7288fd2ae3a2.png)
![](https://img.xkw.com/dksih/QBM/2016/5/20/1572643202678784/1572643208347648/STEM/f126915e67d24850b4717b1d83fc697d.png)
(1)在网格中画出四棱准
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6153163fecdf3f410411048428ccaef5.png)
(2)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4237f6a1fc115bb790aa10704b7908c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
(3)在棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31c34b18525831f3eda7bb90be0199b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b4a0d511365abd9df144a412ccd4615.png)
您最近一年使用:0次