解题方法
1 . 为了研究网民的上网习惯,某机构随机抽取了年龄在10岁到60岁的网民进行问卷调查,按年龄分为5组,即
,
,
,
,
,并绘制出频率分布直方图,如图所示.若按分层抽样的方法,从上述网民中抽取n人做采访,其中年龄在
中被抽取的人数为7,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f3cb8d72bb2e281b943b3b430138ef7.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4990ce494ad28297532c6e3818f7a4f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f4b0d8b0cae9a57ba7aa958b2ef572b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/242cfe1efa903a3006579961bea3ddac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1720e1256b8eb4fa308d77814edaf197.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ab53811235a6aee1c8a7908983b7ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/242cfe1efa903a3006579961bea3ddac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f3cb8d72bb2e281b943b3b430138ef7.png)
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2 . 若
,
是两条不同的直线,
是一个平面,
,则“
”是“
”的( ).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e380108ba2cf04e68a5a9393d2b921c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dedfa42c16dd0aefa2928a6e41f3dba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6a4c549e7ea8776ec821c467bc1a913.png)
A.充分不必要条件 | B.必要不充分条件 |
C.充要条件 | D.既不充分也不必要条件 |
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解题方法
3 . 已知当
时,不等式
恒成立,则实数a的取值范围是______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08115d6d9f876dea921a4d32260ff1fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74b6ce9accae1555dce9a443fda05acc.png)
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4 . 如图,在平行四边形
中,
,点E满足
,则
( ).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d1aa922b038bd7247741f895e192568.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bd26e89314a2076e01f442ed95c5fb4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd27dd5543eabc922bdbe03eb5bfd496.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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5 . 一个圆柱的底面直径和高都等于球
的直径,则球
与该圆柱的体积之比为( ).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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解题方法
6 . 三个数
,
,
之间的大小关系为( ).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a525e811ffc32387348f431b04c32225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ba7fdfc01da5783c330b1f54d96c442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f710d089de64927605639ec0d64ddfcc.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
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7 . 已知向量
,
,
.
(1)若
,求
的值;
(2)若
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fda3f2bbb62d0e0abc140c174944aa89.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d88a1983547e8f6d13e5f7f1cb521dec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41c79ec1cb1bcbcc86b2077957ce6c55.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a36228810d0c2f6c6e53584c1ac176b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c66dc9c4258a666e90278e33e084fdba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83634e314df24df73ae37d25a44d20e3.png)
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8 . 若一组数据
的方差是5,则数据
的方差是__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fe1c31a81f198c443e71b83ca662939.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0539afa6a847e42683ddc877e5264b8d.png)
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名校
9 . 已知一个样本由三个
,三个
和四个
组成,则这个样本的标准差![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9c7e7449010436e00dce3b6924a4258.png)
______
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8c4c029e552954bd493b49aeab82d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d91e07104b699c4012be2d26160976a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9c7e7449010436e00dce3b6924a4258.png)
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名校
10 .
中,角
的对边分别为
,若
,
,
,则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65397f11ea8af736f38debadf420c4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5742b2684d00be50a66e01c9acb6b51f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99f2f1eb2beb23690f56a68dc7da08cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1f9fabbbe61a759e52ec975215e2e7c.png)
A.![]() | B.![]() |
C.![]() ![]() | D.![]() ![]() |
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