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1 . 从某小区抽取50户居民进行月用电量调查,发现其用电量都在50到350度之间,将用电量的数据绘制成频率分布直方图如下.
![](https://img.xkw.com/dksih/QBM/2018/4/13/1923321674727424/1924021284544512/STEM/60f9b90d3d4b45eca6793791934f3d7e.png?resizew=329)
(1)求频率分布直方图中
的值并估计这50户用户的平均用电量;
(2)若将用电量在区间
内的用户记为
类用户,标记为低用电家庭,用电量在区间
内的用户记为
类用户,标记为高用电家庭,现对这两类用户进行问卷调查,让其对供电服务进行打分,打分情况见茎叶图:
![](https://img.xkw.com/dksih/QBM/2018/4/13/1923321674727424/1924021284544512/STEM/3f5a2b37d23647d6a30ad334741a8d8f.png?resizew=362)
①从
类用户中任意抽取3户,求恰好有2户打分超过85分的概率;
②若打分超过85分视为满意,没超过85分视为不满意,请填写下面列联表,并根据列联表判断是否有
的把握认为“满意度与用电量高低有关”?
附表及公式:
,
.
![](https://img.xkw.com/dksih/QBM/2018/4/13/1923321674727424/1924021284544512/STEM/60f9b90d3d4b45eca6793791934f3d7e.png?resizew=329)
(1)求频率分布直方图中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)若将用电量在区间
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27021654e26c879b0ca067e14425ff63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bd912af5e2a64028abe0ef1e2dfe604.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://img.xkw.com/dksih/QBM/2018/4/13/1923321674727424/1924021284544512/STEM/3f5a2b37d23647d6a30ad334741a8d8f.png?resizew=362)
①从
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
②若打分超过85分视为满意,没超过85分视为不满意,请填写下面列联表,并根据列联表判断是否有
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b399e6815afcaa24f2889e58c79c10a1.png)
满意 | 不满意 | 合计 | |
![]() | |||
![]() | |||
合计 |
附表及公式:
![]() | 0.050 | 0.010 | 0.001 |
![]() | 3.841 | 6.635 | 10.828 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bc485c58dbd6e50bfb352030f4a1c42.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/356b05e46b10ee51c3e43546d73ec96c.png)
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2018-04-14更新
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6卷引用:海南省2018届高三第二次联合考试数学理试题