class frequency is: 选项： A:the number of
第一章 什么是统计学 第一单元测试
1、 问题:The general process of gathering， organizing， summarizing， analyzing， and interpreting data to assist in making effective decisions is called:
选项：
A:statistics.
B:descriptive statistics.
C:inferential statistics.
D:levels of measurement.
答案: 【statistics.】
2、 问题:A sample is:
选项：
A:at least 15 observations.
B:a group of people.
C:part of a population.
D:a set of frequencies.
答案: 【part of a population.】
3、 问题:The main purpose of inferential statistics is to:
选项：
A:summarize data in a useful and informative manner.
B:estimate population characteristics based on a sample information.
C:determine if the data adequately represents the population.
D:gather or collect data.
答案: 【estimate population characteristics based on a sample information.】
4、 问题:To study the characteristics of loan applicants， a random sample of 50 loan applicants is selected and their annual incomes are obtained. Which level of measurement is annual income?
选项：
A:Nominal
B:Ordinal
C:Interval
D:Ratio
答案: 【Ratio】
5、 问题:The main purpose of descriptive statistics is to:
选项：
A:summarize data in a useful and informative manner.
C:determine if the data adequately represents the population.
D:gather or collect data.
答案: 【summarize data in a useful and informative manner.】
6、 问题:A bank asks customers to evaluate the quality of drive-through service as good， average， or poor. Which level of measurement is used to measure service quality?
选项：
A:Nominal
B:Ordinal
C:Interval
D:Ratio
答案: 【Ordinal】
7、 问题:The main purpose of descriptive statistics is to:
选项：
A:summarize data in a useful and informative manner.
B:estimate a population characteristic based on a sample.
C:determine if the data adequately represents the population.
D:gather or collect data.
答案: 【summarize data in a useful and informative manner.】
8、 问题:Gallup political polls ask people their political party affiliation – Democrat， Republican or Independent. Which level of measurement is used to measure party affiliation?
选项：
A:Nominal
B:Ordinal
C:Interval
D:Ratio
答案: 【Nominal】
9、 问题:What type of variable is: number of car accidents reported in your city?
选项：
A:Attribute
B:Continuous
C:Discrete
D:Qualitative
答案: 【Discrete】
10、 问题:Data measured with an ordinal scale:
选项：
A:can be ranked.
B:have a meaningful value of zero.
C:have meaningful differences between values.
D:are quantitative.
答案: 【can be ranked.】
第二章 Chapter 2 Describing Data： Frequency Tables， Frequency Distributions， and Graphic Presentation 第
1、 问题:In a frequency distribution the classes must:
选项：
A:be mutually exclusive.
B:have a maximum of 10 observations.
C:have equal frequencies.
D:be measured on a nominal scale.
答案: 【be mutually exclusive.】
2、 问题:For a frequency distribution， the class interval is:
选项：
A:the class frequencies divided by two.
B:the class frequency divided by the number of observations.
C:the difference between consecutive lower class limits.
D:the number of observations in the class.
答案: 【the difference between consecutive lower class limits.】
3、 问题:For a frequency distribution， a class frequency is:
选项：
A:the number of observations in the class.
B:the difference between consecutive lower class limits.
C:limited to a maximum of 10 observations.
D:the total number of observations in the sample.
答案: 【the number of observations in the class.】
4、 问题:A research organization is studying the selling price of laptop computers. They selected 25 different computers for the study. To summarize the selling price with a frequency distribution and using the 2k rule， how many classes would you recommend?
选项：
A:10
B:25
C:4
D:5
答案: 【5】
5、 问题:For a frequency distribution， the class midpoint is:
选项：
A:the class interval divided by two and added to the lower limit.
B:the difference between consecutive lower limits.
C:the number of observations in the class.
D:the class frequency divided by the number of observations.
答案: 【the class interval divided by two and added to the lower limit.】
6、 问题:Which of the following is not a guideline for a frequency distribution?
选项：
A:Avoid open-ended classes.
B:Use the 2k rule to determine the number of classes.
C:Make the lower limit of the first class a multiple of the class interval.
D:Each class should have more than 5 observations.
答案: 【Each class should have more than 5 observations.】
7、 问题:To convert a frequency distribution to a relative frequency distribution:
选项：
A:find the difference between consecutive lower class limits.
B:divide the class frequency by the total number of observations.
C:divide the lower limit of the first class by the class interval.
D:multiple the class frequency by 100.
答案: 【divide the class frequency by the total number of observations.】
8、 问题:A pie chart shows:
选项：
A:the frequency for each class.
B:the relative frequency for each class.
C:trends in the data.
D:the class midpoints.
答案: 【the relative frequency for each class.】
9、 问题:The difference between a histogram and a frequency polygon is:
选项：
A:the frequency polygon is reported as a percent， a histogram does not report percents.
B:the histogram shows frequencies while a frequency polygon shows cumulative frequencies.
C:the bars in a histogram and a frequency polygon cannot be adjacent.
D:open-ended classes can be accommodated with a frequency polygon.
答案: 【the histogram shows frequencies while a frequency polygon shows cumulative frequencies.】
10、 问题:In a cumulative frequency polygon:
选项：
A:the class frequencies are converted to percents.
B:the cumulative frequency for the first class limit is zero.
C:we add the class frequencies starting with the first class.
D:all of the above.
答案: 【all of the above.】
第三章 Chapter 3 Describing Data： Numerical Measures 第三单元测验
1、 问题:A key difference between calculating the sample mean and the population mean is:
选项：
A:we use and n instead of μ and N.
B:we divide the sum of the observations by n – 1 instead of n.
C:the sample observations are ranked and the middle value is selected as the population mean.
D:there are no differences.
答案: 【we use and n instead of μ and N.】
2、 问题:Which of the following measures of central location is affected most by extreme values?
选项：
A:Median
B:Mean
C:Mode
D:Variance
答案: 【Mean】
3、 问题:The Empirical Rule states that:
选项：
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observations in the class. B:the differ