解题方法
1 . 某市为了制定合理的节电方案,供电局对居民用电情况进行了调查,通过抽样,获得了某年
户居民每户的月均用电量(单位:度),将数据按照
,
,
,
,
,
,
,
,
分成9组,制成了如下图所示的频率分布直方图.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/6/9242dd3b-646f-46e1-97ad-4bab978c4bd1.png?resizew=333)
(1)求频率分布直方图中
的值并估计居民月均用电量的中位数;
(2)从样本中月均用电量不低于700度的用户中随机抽取4户,用
表示月均用电量不低于800度的用户数,求随机变量
的分布列及数学期望.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90dd550e1ad9bbf01687ffb4aab788ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b2f96ea940c3488faa2379a491b2536.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/866a5c0242a51b8e87607e3aac1ea86b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f810ca562b2f935e0445b197bb01b967.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cca1ea8729e96da57d1f100f7dace530.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec0cd1bc3f31bd6a7c1deba52e758d3a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b7e28a55d07a1e3d2e2ffec1c4c803e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b51b66c048a9a18a24a0e0ff8c675e7c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2765689722d4c6750abea215cdf58252.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac2dbbbdb186de28ea9227ef758948c1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/6/9242dd3b-646f-46e1-97ad-4bab978c4bd1.png?resizew=333)
(1)求频率分布直方图中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
(2)从样本中月均用电量不低于700度的用户中随机抽取4户,用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
您最近一年使用:0次
2017-03-15更新
|
987次组卷
|
4卷引用:2017届河南省焦作市高三下学期第二次模拟考试数学(理)试卷
2017届河南省焦作市高三下学期第二次模拟考试数学(理)试卷2017届河南省天一大联考高三阶段性测试(四)(b卷) 数学(理)试卷(已下线)2018年5月19日 周末培优——《每日一题》2017-2018学年高二理科数学人教选修2-3(已下线)2019年5月2日 《每日一题》理数选修2-3-离散型随机变量的均值与方差(2)
2011·河南焦作·一模
2 . 为了比较两种肥料
对同类橘子树产量的影响(此处橘子树的产量是指每一棵橘子树的产量,单位是千克),试验人员分别从施用这两种肥料的橘子树中随机抽取了
棵,其中
棵橘子树施用了
种肥料,另
棵橘子树施用了
种肥料作为样本进行分析,其中样本橘子树产量的分组区间为
,
,
,
,
,由此得到表
和图
的所示内容,其中表
是施用
种肥料后橘子树产量的频数分布表,图
是施用
种肥料后橘子树产量的频率分布直方图.
![](https://img.xkw.com/dksih/QBM/2011/4/7/1570106546511872/1570106551934976/STEM/63e1f90a-db2a-46fd-9895-686eec1dfbc1.png?resizew=325)
![](https://img.xkw.com/dksih/QBM/2011/4/7/1570106546511872/1570106551934976/STEM/2928f341-f1ec-45ea-a8a5-3b0b7bfbf7ef.png?resizew=288)
![](https://img.xkw.com/dksih/QBM/2011/4/7/1570106546511872/1570106551934976/STEM/c437caf2-5492-4d76-8ba8-d8fb59bbda70.png?resizew=285)
(Ⅰ)完成图
和表
,其中图
是施用
种肥料后橘子树产量的频率分布直方图,表
是施用
种肥料后橘子树产量的频数分布表,并比较施用
两种肥料对橘子树产量提高的影响那种更大,理由是什么?
表2:施用
种肥料后橘子树产量的频数分布表
(Ⅱ)把施用了
种肥料的橘子树中产量不低于
千克的橘子树记为甲类橘子树,产量小于
千克的橘子树记为乙类橘子树,现采用分层抽样方法从甲、乙两类橘子树中抽取
棵进行跟踪研究,若从抽得的
棵橘子树中随机抽取
棵进行跟踪研究结果的对比,记
为这两颗橘子树中甲类橘子树的个数,求
的分布列.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90dd550e1ad9bbf01687ffb4aab788ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0efba7147f5b9ced8bc4a72f0a9fb8af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0efba7147f5b9ced8bc4a72f0a9fb8af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67c620ae3417443fea2d729f9c26861e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c64cd583c538f89bb8ad7ac2b2e136a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1518f7303c68bd06a664df4716346765.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49af36dc835291b83cf8b5dcc394a01a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e60387030a865e31ae81d19074ed61f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://img.xkw.com/dksih/QBM/2011/4/7/1570106546511872/1570106551934976/STEM/63e1f90a-db2a-46fd-9895-686eec1dfbc1.png?resizew=325)
![](https://img.xkw.com/dksih/QBM/2011/4/7/1570106546511872/1570106551934976/STEM/2928f341-f1ec-45ea-a8a5-3b0b7bfbf7ef.png?resizew=288)
![](https://img.xkw.com/dksih/QBM/2011/4/7/1570106546511872/1570106551934976/STEM/c437caf2-5492-4d76-8ba8-d8fb59bbda70.png?resizew=285)
(Ⅰ)完成图
![](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/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
表2:施用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
橘子树产量的分组 | |||||
频数 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5021dda43ea360fb7b1102c1a462693a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58b184c94e38f1e5dbe750b2168c2a37.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
您最近一年使用:0次