用简单随机重复抽样方法抽取样本单位,如果要使抽样平均误差降低50%,则样本容量需要扩

题型:单项选择题

问题:

用简单随机重复抽样方法抽取样本单位,如果要使抽样平均误差降低50%,则样本容量需要扩大到原来的()倍。

A.2

B.3

C.4

D.5

考点:统计师考试统计学和统计法基础知识抽样推断
题型:单项选择题

阅读理解。

Subject: Complaints

Date: May 30, 2007

From: David@ hotmail.com

To: Glasgow@silverline.com

Dear Sir or Madam,

     Last Thursday, I traveled in the 8:40 am train from Glasgow to London King's Cross and I was very

unhappy with the service provided by your company.

    The train was forty minutes later leaving Glasgow. Although the guard apologized, we were not given

any reasons for the delay. We then had further delays when the train crew changed. We had to wait another

thirty minutes. As a result, I missed my flight from London Heathrow to Frankfurt and had to wait for

several hours. 

    What's more, the service in the train was also very poor. The trip took over five hours. Unluckily, there

was no dining car in the train and only a bar with soft drinks. The worst of all, the air conditioning broke

down halfway through the trip and it got hotter and hotter in the train. However, there was no apology for

this, and before we reached King's Cross, the temperature was over 40℃. In view of the poor service, I

feel I am entitled to compensation. I am looking forward to hearing from you. 

                                                                                                                               Yours faithfully,

                                                                                                                                David Robertson

1. What time did the train start its trip to King's Cross that morning?

    _______________________________________________________________

2. What happened to David because of the delay of the train?

    _______________________________________________________________

3. Why did it get hotter and hotter in the train?

    _______________________________________________________________

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B.越大

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D.为0

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