习题6 管理统计 南京工业大学 张琳 上课讲义

Chapter 6

一、复习思考题

1.什么是抽样推断法？它有什么特点和作用。

2.抽样调查有哪几种不同的组织方式？其主要特点是什么？

3.什么是点估计和区间估计。

4.确定必要的抽样单位数的依据有哪些？怎样确定？

二、判断题

1.抽样误差的大小与样本数目的多少成反比，而与抽样推断的可靠度成正比。（）

2.重复抽样的抽样误差有可能比不重复抽样的抽样误差小。（）

3.抽样误差的产生是由于破坏了随机抽样原则造成的。（）

4.极限抽样误差就是指置信区间，是最大可能的抽样误差范围。（）

三、选择题

（一）单项选择题

1.根据抽样的资料，一年级优秀生比重为10%，二年级为20%，在抽样人数相等的条件下，优秀生的抽样误差（）

⑴一年级较大⑵二年级较大⑶相同⑷无法得出结论

2.根据5%抽样调查资料，甲企业工人平均工资方差为25，乙企业为100，乙企业工人数比甲企业工人数多3倍，则随机抽样误差（）

⑴甲企业大⑵乙企业大⑶相同⑷不能作出结论

3.根据城市电信网的100次通话，已知通话平均时间为4分钟，均方差为2分钟，在概率为95.45%时，通话平均持续时间的极限抽样误差是（）

⑴ 0.2 ⑵ 0.4 ⑶ 0.28 ⑷ 0.14

（二）多项选择题

1.抽样调查与其他非全面调查的主要区别在于（）

⑴是一种专门组织的非全面调查

⑵根据部分实际资料对全部总体的数量特征作出估计

⑶是根据随机原则来抽选样本单位的

⑷抽样推断产生的误差可事先计算并加以控制

⑸调查单位少、调查范围小，可节省调查经费

2.在抽样调查中（）

⑴全及总体是唯一的确定的⑵全及指标是唯一确定的

⑶抽样总体是不确定的⑷抽样指标是随机变量

⑸总体参数是随机变量

四、某校对一年级新生进行英语测验，为了解情况，从参加学生中，随机抽选10%，其100

上的学生所占比重。

五、The following data are from a simple random sample.

5 8 10 7 10 14

1.What is the point estimate of the population mean?

2.What is the point estimate of the population standard deviation?

六、A Louist Harrist poll used a survey of 1008 adults to learn about how people feel about the economy (Business Week, August 7, 2000). Responses were as follow:

595 adults The economy is growing.

332 adults The economy is staying about the same.

81 adults The economy is shrinking.

Develop the point estimate of the following population parameters.

1.The proportion of all adults who feel the economy is growing.

2.The proportion of all adults who feel the economy is staying about the same.

3.The proportion of all adults who feel the economy is shrinking.

七、A survey of first-time home buyers found that the mean of annual household income was $50,000 (CNBC. Com, July 11, 2000). Assume the survey used a sample of 400 first-time home buyers and that the sample standard deviation in income was $20,500. What is the 95% confidence interval for the population mean annual household income for first-time home buyers?

八、The National Center for Education Statistics reported that 47% of college students work to pay for tuition and living expenses (The Tampa Tribune, January 22, 1997). Assume that a sample of 450 college students was used in the study.

1.Provide a 95% confidence interval for the population proportion of college students who work

to pay for tuition and living expense.

2.What happens to the margin of error as the confidence is increased from 95% to 99%?