解题方法
1 . 某地区5000名学生的数学成绩
(单位:分)服从正态分布
,且成绩在
的学生人数约为1800,则估计成绩在100分以上的学生人数约为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2c6d9dd3a52e6ba1d2bb623909974dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13a0dc3b0349c53d7bf36dfe97958cea.png)
A.200 | B.700 | C.1400 | D.2500 |
您最近一年使用:0次
2 . 某种食盐的袋装质量
服从正态分布
,随机抽取10000袋,则袋装质量在区间
的约有______ 袋.(质量单位:g)
附:若随机变量
服从正态分布
,则
,
,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f13a2b2475ebd10020ef010c5826357b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bae0fc48f81b6d853e6007048fc58e0e.png)
附:若随机变量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29bcc248a7770a16fa10fc4602d71e0e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a73c92c442a142d4e5fc618dc00bcf30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b65e903fb7fe549c73f55779df19729f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/112b77b25edccc41e2253c5b779d107e.png)
您最近一年使用:0次
2023-03-10更新
|
1161次组卷
|
4卷引用:河北省唐山市2023届高三一模数学试题
河北省唐山市2023届高三一模数学试题河北省邢台市名校联盟2023届高三下学期3月模拟(二)数学试题江苏省南通市如皋市2024届高三上学期期初考试押题卷数学试题(已下线)上海市静安区2023届高三二模数学试题变式题11-15
名校
3 . 苹果可按果径
(最大横切面直径,单位:
.)分为五个等级:
时为1级,
时为2级,
时为3级,
时为4级,
时为5级.不同果径的苹果,按照不同外观指标又分为特级果、一级果、二级果.某果园采摘苹果10000个,果径
均在
内,从中随机抽取2000个苹果进行统计分析,得到如图1所示的频率分布直方图,图2为抽取的样本中果径在80以上的苹果的等级分布统计图.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/17/b6a1689b-09e9-442f-aaaf-234ef98657b2.png?resizew=494)
(1)假设
服从正态分布
,其中
的近似值为果径的样本平均数
(同一组数据用该区间的中点值代替),
,试估计采摘的10000个苹果中,果径
位于区间
的苹果个数;
(2)已知该果园今年共收获果径在80以上的苹果
,且售价为特级果12元
,一级果10元
,二级果9元
.设该果园售出这
苹果的收入为
,以频率估计概率 ,求
的数学期望.
附:若随机变量
服从正态分布
,则
,
,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9c214cc074cf24aa90f2dfb01de102a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d01863e09cc482045451e2a59c36c0f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6704adaa5612cae6683ed875aac26e31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4ca64e7f17eca0c81e72863e7c91abe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ccb954d389c9f3d857c68a33063fdf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e7fdd5967a44570e4b28f0069edf6b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38bbd593ef77de56108b50ece55317c6.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/17/b6a1689b-09e9-442f-aaaf-234ef98657b2.png?resizew=494)
(1)假设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e84c2c26cbb6b22a415fd0830401aeac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1100379a4385b9ce064847bc21760adc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfbe7f95b5d89f9409ec24536da9e826.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ed11061433dd934ae0f08e0901bf859.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9da87f4151ac743255cdffc389c5f8b.png)
(2)已知该果园今年共收获果径在80以上的苹果
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/529579e128e1849a9d41bd89c91cbd15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aef981ba3c6ad98644bdddf25e9a97f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aef981ba3c6ad98644bdddf25e9a97f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aef981ba3c6ad98644bdddf25e9a97f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/529579e128e1849a9d41bd89c91cbd15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
附:若随机变量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d8b9ad2fcfff3dd546c5fdbedfe6238.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e84c2c26cbb6b22a415fd0830401aeac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ddaac69b8713d60c7be617b2e7558784.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6e4c0efeee064ca2b0d3493dfac0c46.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e77a3075193e45f5ee4f791852f43446.png)
您最近一年使用:0次
2019-04-18更新
|
1371次组卷
|
2卷引用:【市级联考】河北省唐山市2019届高三第二次模拟考试数学(理)试题