已知 {an} 是等比数列， a2=2 ， a5=14 ，则公比 q 等于

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已知 {an} 是等比数列， a2=2 ， a5=

1

4

，则公比 q 等于（）

A： $\sqrt{2}$

B： $\frac{1}{2}$

C： $\frac{1}{4}$

D： $- \frac{1}{2}$

上一题下一题 0.0难度选择题更新时间:2019-05-18 08:45:21

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B

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信息归纳，请根据短文内容，完成信息表。

What's your hobby? Last Friday, the School Student Union made a survey about this. The following are the ideas of four middle school students.

I like playing football very much. I think it is one of the most popular ways to relax. And it can help me grow stronger. I often play football on PE lesson and after school. In this way I make friends with a lot of football-likers. (Li Xiaofeng)

My hobby is singing. It's a great hobby! Singing can be used to relieve(解除) my fatigues(疲劳).Singing makes me happy when I'm sad. While I am singing songs, I can share other's joys and sorrow(悲痛) in the life. I really enjoy singing. I keep practicing singing every day. And I hope to become a singer one day.(Yuan Zhihua)

I am a 15-year-old student in Junior Grade 3. Though I am occupied with my study, I would like to spend time on my hobbies. One of my hobbies is reading. It can not only kill the time, but also, more important, help improve my comprehension ability. While reading, I can learn a lot. (Chen Jiayao)

Online games are my favorite. I spend lots of time playing on-line games every day. In this way I have made many friends. I think online games make me clever and confident, thought I am not good at my lessons. （Liu Wei）

Information Card

Name	Hobby	Reasons
Li Xiaofeng	Playing football	Help him grow stronger and ____.
Yuan Zhihua	Singing	．____and make her happy.
Chen Jiayao	____	____ and help improve comprehension ability.
Liu Wei	Playing online games	Help to make friends and make him____.

同类题4

海水养殖场进行某水产品的新、旧网箱养殖方法的产量对比，收获时各随机抽取了100个网箱，测量各箱水产品的产量（单位：kg），其频率分布直方图如下：

（Ⅰ）记A表示时间“旧养殖法的箱产量低于50kg”，估计A的概率；

（Ⅱ）填写下面列联表，并根据列联表判断是否有99%的把握认为箱产量与养殖方法有关：

	箱产量＜50kg	箱产量≥50kg
旧养殖法
新养殖法

（Ⅲ）根据箱产量的频率分布直方图，对两种养殖方法的优劣进行比较．

附：

P（K²≥K）	0.050	0.010	0.001
K	3.841	6.635	10.828

K²= $\frac{n {(a d - b c)}^{2}}{(a + b) (c + d) (a + c) (b + d)}$ ．

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