名校
1 . 上周联考的数学成绩
服从正态分布
,且
,负责命题的王老师考后随机抽取了
个学生的数学成绩,设这
个学生中得分在
的人数为
,则随机变量
的方差为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f230da6e1c3366909b743a9858a59c85.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fe0493a00a0a8e1fba774956655c348.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d07ae0b4264da6a8812454ffd2f20d94.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d07ae0b4264da6a8812454ffd2f20d94.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1f2fc3fd44507a8939677f03e883a5d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a829fdd8ec0f3b7ede883cf2c3e53b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a829fdd8ec0f3b7ede883cf2c3e53b.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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2 . 已知圆
,直线
,方程
,则“圆
与直线
相切”是“方程
表示的曲线为椭圆”的( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cadc2a6ae4ac51ad58567d0a352befd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b03c995df016f9f211f419995919d045.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89e11b62c6594899bbc96c1547210f1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
A.充分非必要条件 | B.必要非充分条件 | C.充要条件 | D.既非充分也非必要条件 |
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3 . 已知向量
,
,若
,则实数![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd707b69a11f8de5566f23c1a2a9ff5a.png)
____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ffae21e88fc79b0def6b7285bed8624.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32cde768af0b6520211805e04decb739.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7dced91de1b8c38aa95ffee0e5dc202.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd707b69a11f8de5566f23c1a2a9ff5a.png)
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解题方法
4 . 如果一个等差数列前10项的和为54,最后10项的和为146,且所有项的和为390,则这个数列有( )
A.36项 | B.37项 | C.38项 | D.39项 |
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解题方法
5 . 有三个房间需要粉刷,粉刷方案要求:每个房间只用一种颜色,且三个房间颜色各不相同.已知三个房间的粉刷面积(单位:
)分别为
,且
,三种颜色涂料的粉刷费用(单位:元
)分别为
,且
,在不同的方案中,最低的总费用(单位:元)是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba007666deb89951641bd1e24bc174a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a14c388e1e2e5a2ff1ccf6caffbee0d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1afddac11c3055bdef861f32a44da384.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69d81273a33e222e53d3ee891c508643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b73abfe4bc26b1ded680d7abb1a2cac.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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6 . 复数
在复平面内分别对应点
,
,将点
绕原点
按顺时针方向旋转
得到点
,则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90d860cb86e1467ac24010aecfc7a425.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22214f48085c06e62521bf96c27191b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c02b54dc6b3e1bb6544f47d4c8743fcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69a7516303b3dd7c28b3b3fcffd538ca.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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解题方法
7 . 若函数
为偶函数,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/380bbacf854e30e2e747fc286d2b9997.png)
__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ddc2c2ca79967bfd44d54a488712508.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/380bbacf854e30e2e747fc286d2b9997.png)
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名校
8 . 某果园产苹果,其中一堆苹果中大果与小果的比例为
.
(1)若选择分层抽样,抽出100个苹果,其中大果的单果平均质量为240克,方差为300,小果的单果平均质量为190克,方差为320,试估计果园苹果平均质量、方差;
(2)现用一台分选机筛选,已知这台分选机把大果筛选为小果的概率为
,把小果筛选为大果的概率为
,经过分选机筛选后,现从“大果”里随机抽取一个,求这个“大果”是真的大果的概率.
参考公式:样本划分为2层,各层的容量、平均数和方差分别为:
,
,
;
,
,
.记样本平均数为
,样本方差为
,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/320896d1b4b9217d9ba527604ac35d3d.png)
(1)若选择分层抽样,抽出100个苹果,其中大果的单果平均质量为240克,方差为300,小果的单果平均质量为190克,方差为320,试估计果园苹果平均质量、方差;
(2)现用一台分选机筛选,已知这台分选机把大果筛选为小果的概率为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f733b1ceeead9ff892539d46a23f3626.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ad2925d2ce0e1e8ef352f9501f2590d.png)
参考公式:样本划分为2层,各层的容量、平均数和方差分别为:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c85481cd7e94130ef3aa05b4a39e79cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dfbc29b47b83fdc5368770b7b1acb439.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/923d80da4a6cb5f102be334006d875a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab1295cbd36fdc55a55b549aa2dd5887.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c82359e2d8f541e44c6be90a390f33ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/671f43c79d612c93a6d160335e86e177.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b880e98674bab74e6068ef1861a8ddf.png)
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9 . 面试是求职者进入职场的一个重要关口,也是机构招聘员工的重要环节.某科技企业招聘员工,首先要进行笔试,笔试达标者才能进入面试.面试环节要求应聘者回答3个问题,第一题考查对公司的了解,答对得1分,答错不得分;第二题和第三题均考查专业知识,每道题答对得2分,答错不得分.
(1)根据近几年的数据统计,应聘者的笔试得分
服从正态分布
,要求满足
为达标.现有1000人参加应聘,求进入面试环节的人数.(结果四舍五入保留整数)
(2)某进入面试的应聘者第一题答对的概率为
,后两题答对的概率均为
,每道题是否答对互不影响,求该应聘者的面试成绩
的分布列与数学期望.
附:若
,则
,
(1)根据近几年的数据统计,应聘者的笔试得分
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e00cbe5142125a2bb5aa2dc650670a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e562f0b6d757c6d575497730c6d0237.png)
(2)某进入面试的应聘者第一题答对的概率为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf31876698721a199c7c53c6b320aa86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7294f5ae2a24ff42e84cd9773b2a7287.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a829fdd8ec0f3b7ede883cf2c3e53b.png)
附:若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23712e1f47e4e91df9cadd4e5c4a6692.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ec7b7a417d3cb1c30b19b187d00390c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797208aa4da483bb74b6f594be160cde.png)
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10 . 若复数
满足
,则
的虚部为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e81e59019989b7dc2fb59b037ef6e010.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ae028b3c74e2b11f9eacf743658f803.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d41042207515dd2e8349c805e6aee400.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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