2021知到答案 商务统计冬学期 智慧树满 分章节测试答案

绪论 章节测试

1、选择题:

Penny Bauer, Chief Financial Officer of Harrison Haulage, suspects irregularities in the payroll system, and orders an inspection of ‘each and every payroll voucher issued since 1 January 2005’. Five per cent of the payroll vouchers contained material errors. This is an example of ________________.

选项：
A:descriptive statistics
B:nominal data
C:nonparametric statistics
D:inferential statistics
答案: 【descriptive statistics】

第一章 章节测试

1、选择题:Michael Bayley, Marketing Director of UniPower’s Electrical Division, is leading a study to identify and assess the relative importance of product features. Michael directs his staff to design a survey questionnaire for distribution to all of UniPower’s 954 customers. For this study, the set of 954 customers is a ________________.
选项：
A:population
B:

sample

C:

parameter

D:

statistic

答案: 【population
】
2、选择题:Claudia Taylor, Director of Global Industrial Sales in Melbourne, is concerned by a deteriorating sales trend. Specifically, the number of customers is stable at 1500 but they are purchasing less each year. She orders her staff to search for causes of the downward trend by selecting a focus group of 40 industrial customers. For this study, the set of 40 industrial customers is a _______.
选项：
A:population
B:statistic
C:sample
D:parameter
答案: 【sample
】
3、选择题:A politician who is running for the office of premier in a state with 3 million registered voters commissions a survey. In the survey, 53.6% of the 5000 registered voters interviewed say they plan to vote for him. The population of interest is the
选项：
A:53.6 % of, or 2680, voters interviewed who plan to vote for him
B:5000 registered voters interviewed.
C:46.4% of, or 2320, voters interviewed who plan not to vote for him
D:3 million registered voters in the state.
答案: 【3 million registered voters in the state.
】
4、选择题:Simon Arnett, Director of Human Resources, is exploring the causes of employee absenteeism at Buderim Bottling during the last operating year (1 January 2005 to 31 December 2005). The average number of absences per employee, calculated from the personnel data of all employees, is a ___________________.
选项：
A:sample
B:population
C:statistic
D:parameter
答案: 【parameter
】
5、选择题:A summary measure that is computed from a sample to describe a characteristic of the population is called
选项：
A:a parameter
B:a population
C:Both A and C are correct, since they are the same
D:a statistic
答案: 【a statistic
】
6、选择题:Simon Arnett, Director of Human Resources, is exploring the causes of employee absenteeism at Buderim Bottling during the last operating year (1 January 2005 to 31 December 2005). Personnel records of 50 employees are selected for analysis. (The plant employs 250.) For this study, the average number days absent for these 50 employees is a ________________.
选项：
A:population
B:statistic
C:sample
D:parameter
答案: 【statistic
】
7、选择题:Descriptive statistics deals with methods of
选项：
A:presenting data in a convenient and informative way
B:summarising data
C:doing all of the above
D:organising data.
答案: 【doing all of the above
】
8、选择题:Which of the following statements is not true?
选项：
A:Statistical inference is used to draw conclusions or inferences about characteristics of populations based on sample data
B:In the language of statistics, the term population refers to a group of people
C:One form of descriptive statistics uses graphical techniques
D:One form of descriptive statistics uses numerical techniques
答案: 【In the language of statistics, the term population refers to a group of people
】
9、选择题:A student achieves an 82 on the first test in a statistics course. From this, she assumes that her average at the end of the semester (after other tests) will be about 82. This is an example of ___________________.
选项：
A:nonparametric statistics
B:wishful thinking
C:descriptive statistics
D:inferential statistics
答案: 【inferential statistics
】
10、选择题:Which of the following is not the goal of descriptive statistics?
选项：
A:

Reporting numerical findings

B:Displaying aspects of the collected data
C:Estimating characteristics of the population
D:Summarising data
答案: 【Estimating characteristics of the population
】

第二章 章节测试

1、选择题: If data are grouped into intervals and the number of items in each group is listed, this could be called a _______________.
选项：
A:histogram
B:ogive
C:frequency distribution
D:stem and leaf plot
答案: 【histogram
】[$]
2、选择题:If the individual class frequency is divided by the total frequency, the result is the __________.
选项：
A:midpoint frequency
B:stem and leaf plot
C:

cumulative frequency

D:relative frequency
答案: 【relative frequency
】
3、选择题:A cumulative frequency polygon is also called _______________.
选项：
A:a frequency polygon
B:a stem and leaf plot
C:an ogive
D:a histogram
答案: 【an ogive
】
4、选择题:The number of class intervals in a frequency distribution is usually between ___________.
选项：
A:5 and 15
B:3 and 5
C:1 and 25
D:7 and 9
答案: 【5 and 15
】
5、选择题:One advantage of a stem and leaf plot over a frequency distribution is that __________.
选项：
A:the class midpoints are used as the leaf
B:it contains more class intervals
C:the values of the original data are retained
D:

the class midpoints are used as the stem

答案: 【the values of the original data are retained
】
6、选择题:One rule that must always be followed in constructing frequency distributions is that ________.
选项：
A:the number of intervals must be an odd number
B:the number of classes must be less than 10
C:the width of each class is equal to the range
D:

each data point can only fall into one class

答案: 【

each data point can only fall into one class

】
7、选择题:Which of the following is best to show the percentage of a total budget that is spent on each category of items?
选项：
A:histogram
B:pie chart
C:ogive
D:stem and leaf chart
答案: 【pie chart
】
8、选择题:A cumulative frequency distribution would provide _____________.
选项：
A:a graph of a frequency distribution
B:the proportion of the total frequencies which fall into each class
C:a running total of the frequencies in the classes
D:a very cloudy picture of the frequencies
答案: 【a running total of the frequencies in the classes
】
9、选择题:The number of phone calls arriving at a switchboard each hour has been recorded and the following frequency distribution has been developed.

What is the cumulative frequency of the third class?
选项：
A:0.40
B:75
C:80
D:155
答案: 【155
】
10、选择题:The number of phone calls arriving at a switchboard each hour has been recorded and the following frequency distribution has been developed.

What is the approximate range of the number of phone calls arriving each hour?
选项：
A:100
B:200
C:80
D:20
答案: 【80】

第三章 章节测试

1、选择题:Simon Arnett, Director of Human Resources, is exploring employee absenteeism at the Buderim Bottling during the last operating year. A sample of six personnel records produced the following data: 0, 2, 4, 7, 2, 9. The variance of the number absences per employee is ____________.
选项：
A:3.41
B:3.11
C:9.67
D:11.6
答案: 【11.6】
2、选择题:Jessica Salas, Managing Director of Salas Products, is reviewing the warranty policy for her company’s new model of car batteries. Life tests performed on a sample of 100 batteries indicated: (1) an average life of 75 months, (2) a standard deviation of 5 months, and (3) battery life is approximately normally distributed. Approximately 68% of the batteries will last between ________________.
选项：
A:70 and 80 months
B:60 and 90 months
C:55 and 95 months
D:65 and 85 months
答案: 【70 and 80 months
】
3、选择题:The average starting salary for graduates at a university is $25,000 with a standard deviation of $2000. A histogram of the data shows the shape to be very erratic so Chebyshev’s Theorem should be used. How many of the graduates would have a starting salary between 21,000 and 29,000?
选项：
A:at least 89%
B:at least 95%
C:at least 68%
D:at least 75%
答案: 【at least 75%
】
4、选择题:The sample standard deviation is found by taking the square root of _______.
选项：
A:the sample variance
B:

the sample mean

C:the mean absolute deviation
D:the coefficient of variation
答案: 【the sample variance
】
5、选择题:The number of standard deviations that a value (X) is above or below the mean is the _______.
选项：
A:interquartile range
B:Z score
C:absolute deviation
D:coefficient of variation
答案: 【Z score
】
6、选择题:In a histogram, the proportion of the total area that must be to the left of the median is（ ）
选项：
A:less than 0.50 if the distribution is skewed to the left
B:exactly 0.50.
C:more than 0.50 if the distribution is skewed to the right
D:between 0.25 and 0.60 if the distribution is symmetric and unimodal
答案: 【exactly 0.50.
】
7、选择题:Which of the following is NOT a measure of central tendency?
选项：
A:variance
B:mean
C:mode
D:median
答案: 【variance
】
8、选择题:Another term for average is ____________.
选项：
A:median
B:mean
C:mode
D:variance
答案: 【mean
】
9、选择题:If the mean of a distribution is greater than the median, then the distribution is ____________.
选项：
A:skewed to the left
B:skewed to the right 
C:not skewed
D:symmetrical about its mean
答案: 【skewed to the right 
】
10、选择题:The mean is not affected by the extreme values.
选项：
A:错
B:对
答案: 【错】

第四章 章节测试

1、选择题:A process that produces outcomes is called _______.
选项：
A:an experiment
B:population equivalent
C:an event
D:a result
答案: 【an experiment
】
2、选择题:Which of the following is NOT a legitimate probability value?
选项：
A:0.23
B:15/16
C:0.67
D:4/3
答案: 【4/3
】
3、选择题:An outcome of an experiment is called _______.
选项：
A:a priori elements
B:a complement
C:an event
D:a probability
答案: 【an event
】
4、选择题:The list of all elementary events for an experiment is called _______.
选项：
A:the exhaustive list
B:the sample space
C:the population space
D:the event union
答案: 【the sample space
】
5、选择题:If A and B are mutually exclusive events with P(A) = 0.70, then P(B)：（ ）
选项：
A:cannot be larger than 0.30
B:can take any value between 0 and 1
C:cannot be determined from the information given
D:can take any value between 0 and 0.70
答案: 【cannot be larger than 0.30
】
6、选择题:If an event is in set X but is not in set Y, which of the following is true?
选项：
A:it is in both the union and intersection of X and Y
B:it is not in the union of X and Y
C:

it is in the union of X and Y

D:it is in the intersection of X and Y
答案: 【

it is in the union of X and Y

】
7、选择题:If the occurrence of one event does not affect the occurrence of another event, then the two events are _______.
选项：
A:mutually exclusive
B:complements
C:independent
D:elementary events
答案: 【independent
】
8、选择题:Let A be the event that a student is enrolled in an accounting course, and let S be the event that a student is enrolled in a statistics course. It is known that 30% of all students are enrolled in an accounting course and 40% of all students are enrolled in statistics. Included in these numbers are 15% who are enrolled in both statistics and accounting. Find P(S).
选项：
A:0.40
B:0.30
C:0.55
D:0.15
答案: 【0.40】
9、选择题:Given P(A) = 0.40, P(B) = 0.50, P(A  B) = 0.15. Which of the following is true?
选项：
A:A and B are not independent
B:A and B are mutually exclusive
C:A and B are independent
D:A and B are collectively exhaustive
答案: 【A and B are not independent
】
10、选择题:Meagan Davies manages a portfolio of 200 common stocks. Her staff classified the portfolio stocks by ‘industry sector’ and ‘investment objective’.

Which of the following is NOT true?
选项：
A:Growth and Income are complementary events.
B:Electronics and Healthcare are mutually exclusive.
C:Electronics and Growth are dependent.
D:Airlines and Healthcare are collectively exhaustive.
答案: 【Airlines and Healthcare are collectively exhaustive.
】

第五章 章节测试

1、选择题:Variables which take on values only at certain points over a given interval are called _______.
选项：
A:continuous random variables
B:discrete random variables
C:point variables
D:value variables
答案: 【discrete random variables
】
2、选择题:A variable that can take on values at any point over a given interval is called _______.
选项：
A:a continuous random variable
B:a discrete random variable
C:a value variable
D:a point variable
答案: 【a continuous random variable
】
3、选择题:You are offered an investment opportunity. Its outcomes and probabilities are presented in the following table.

The mean of this distribution is _____________.
选项：
A:$200
B:$0
C:–$400
D:$400
答案: 【$0】
4、选择题:You are offered an investment opportunity. Its outcomes and probabilities are presented in the following table.

The standard deviation of this distribution is _____________.
选项：
A:$800,000
B:$894
C:–$400
D:$663
答案: 【$894
】
5、选择题:The long-run average or mean of a Poisson distribution is usually referred to as _______.
选项：
A:l
B:m
C:a
D:s
答案: 【l
】
6、选择题:The variance of a Poisson distribution is equal to _______.
选项：
A:l/2
B:l
C:l2
D:
答案: 【l
】
7、选择题:If X is a binomial random with n = 8 and p = 0.6, what is the probability that X is less than or equal to 2?
选项：
A:0.050
B:0.041
C:0.375
D:0.009
答案: 【0.050】
8、选择题:If X is a binomial random with n = 8 and p = 0.6, what is the probability that X is greater than 2?
选项：
A:0.011
B:0.950
C:0.124
D:0.991
答案: 【0.950
】
9、选择题:Twenty-five items are sampled. Each of these has the same probability of being defective. The probability that exactly 2 of the 25 are defective could best be found by _______.
选项：
A:using the Poisson distribution
B:using the normal distribution
C:using the binomial distribution
D:using the exponential distribution
答案: 【using the binomial distribution
】
10、选择题:You are offered an investment opportunity. Its outcomes and probabilities are presented in the following table.

Which of the following statements is true?
选项：
A:This distribution is skewed to the left.
B:This distribution is symmetric.
C:This is a binomial distribution.
D:This distribution is skewed to the right.
答案: 【This distribution is symmetric.
】

第六章 章节测试

1、选择题:The normal distribution is an example of _______.
选项：
A:a discrete distribution
B:an exponential distribution
C:a continuous distribution
D:a bimodal distribution
答案: 【a continuous distribution
】
2、选择题:The total area underneath any normal curve is _______.
选项：
A:equal to 1
B:equal to the variance
C:equal to the mean
D:equal to the coefficient of variation
答案: 【equal to 1
】
3、选择题:The area to the left of the mean in any normal distribution is _______.
选项：
A:equal to 0.5
B:equal to the mean
C:equal to the variance
D:equal to 1
答案: 【equal to 0.5
】
4、选择题:For any normal distribution, any value less than the mean would have a _______.
选项：
A:negative z-score
B:positive z-score 
C:negative probability of occurring
D:

negative variance

答案: 【negative z-score
】
5、选择题:A standardised normal distribution has the following characteristics:
选项：
A:he mean and variance are both equal to 1
B:the mean is equal to the variance
C:the mean is equal to 0 and the variance is equal to 1
D:the mean and variance are both equal to 0
答案: 【the mean is equal to 0 and the variance is equal to 1
】
6、选择题:If X is a normal random variable with mean 80 and standard deviation 5, calculate the z-score if X = 88.
选项：
A:1.8
B:-1.8
C:-1.6
D:1.6
答案: 【1.6】
7、选择题:Suppose X is a normal random variable with mean 60 and standard deviation 2. A z-score was calculated for a number, and the z-score is 3.4. What is x?
选项：
A:63.4
B:66.8
C:56.6
D:53.2
答案: 【66.8】
8、选择题:Let X be a normal random variable with mean 20 and standard deviation 4. Find P(16 < X < 22).
选项：
A:0.1498
B:0.4672
C:0.5328
D:0.0328
答案: 【0.5328
】
9、选择题:Let X be a normal random variable with mean 20 and standard deviation 4. The 90th percentile of X is ____________.
选项：
A:20.000
B:25.126
C:26.579
D:22.698
答案: 【25.126
】
10、选择题:A z-score is the number of __________ that a value is from the mean.
选项：
A:variances
B:standard deviations
C:miles
D:units
答案: 【standard deviations
】

第七章 章节测试

1、选择题:As a general rule, the normal distribution is used to approximate the sampling distribution of the sample mean only if
选项：
A:np and n(1 – p) are both greater than 5
B:the sample size n is sufficiently large
C:the sample mean is close to 0.50.
D:the underlying population is normal
答案: 【the sample size n is sufficiently large
】
2、选择题:The eight employees of the Art Department and their ‘years of experience’ are listed in the following table.

If a sample of three employees is selected with replacement, the number of elementary outcomes in the sample space is _______________.
选项：
A:56
B:512
C:336
D:64
答案: 【512
】
3、选择题:A sampling distribution is a distribution of _______________.
选项：
A:excess profits to selected shareholders.
B:a population parameter, such as, µ.
C:a sample statistic, such as,
D:a population attribute, such as, employee’s age.
答案: 【a sample statistic, such as,】
4、选择题:The standard deviation of a sampling distribution is commonly called _______.
选项：
A:the standard error.
B:statistical margin.
C:statistical leverage.
D:the uniform spread.
答案: 【the standard error.
】
5、选择题:The central limit theorem states that if n is large enough, the distribution of the sample means is _____________ distributed regardless of the shape of the population.
选项：
A:randomly
B:approximately normally
C:nonrandomly
D:uniformly
答案: 【approximately normally
】
6、选择题:According to the central limit theorem, the mean of the sample means for a given size of sample is equal to _______.
选项：
A:the population mean divided by the square root of n
B:the population mean
C:zero
D:the population mean divided by n
答案: 【the population mean
】
7、选择题:Increasing the sample size causes the standard error of the mean to ________.
选项：
A:increase in value
B:decrease in value
C:destabilise in value
D:seek market equilibrium
答案: 【decrease in value
】
8、选择题:Increasing the sample size causes the sampling distribution of  to ________.
选项：
A:shift to the left
B:have less dispersion
C:have more dispersion
D:shift to the right
答案: 【have less dispersion
】
9、选择题:Suppose a population has a mean of 90 and a standard deviation of 28. If a random sample of size 49 is drawn from the population, the probability of drawing a sample with a mean of more than 95 is _______.
选项：
A:0.4286
B:0.8944
C:0.3944
D:0.1056
答案: 【0.1056
】
10、选择题:Suppose 40% of all university students have a computer at home and a sample of 64 is taken. What is the probability that more than 30 of those in the sample have a computer at home?
选项：
A:0.3686
B:0.1314
C:0.6314
D:0.8686
答案: 【0.1314
】

第八章 章节测试

1、选择题:

When a range of values is used to estimate a population parameter, it is called _______.
选项：
A:a point estimate
B:a range estimate
C:

a statistical parameter

D:an interval estimate
答案: 【an interval estimate
】
2、选择题:

Catherine Cho, Director of Marketing Research at Vitalglow Pty Ltd, is evaluating consumer acceptance of a new toothpaste package. Her staff report that 17% of a random sample of 200 Darwin households prefer the new package to all other package designs. If Catherine concludes that 17% of all households prefer the new package, she is using a _______.

选项：
A:a range estimate
B:a statistical parameter
C:a point estimate
D:an interval estimate
答案: 【a point estimate
】

3、选择题:

The z-value associated with a two-sided 90% confidence interval is _______.
选项：
A:1.96
B:2.575
C:1.645
D:1.28
答案: 【1.645
】

4、选择题:

Suppose a random sample of 36 is selected from a population with a standard deviation of 12. If the sample mean is 98, the 99% confidence interval to estimate the population mean is _______.

选项：
A:94.08 to 101.92
B:97.35 to 98.65
C:92.85 to 103.15
D:93.34 to 102.66
答案: 【93.34 to 102.66
】

5、选择题:

Sam Gates, Marketing Director of Mansfield Motors’ Electrical Division, is leading a study to assess the relative importance of product features. An item on a survey questionnaire distributed to 121 Mansfield customers asked them to rate the importance of ‘ease of maintenance’ on a scale of 1 to 10 (with 1 meaning ‘not important’ and 10 meaning ‘highly important’). His staff assembled the following statistics.

The 90% confidence interval for the population mean rating of ‘ease of maintenance’ is _____.
选项：
A:7.30 to 7.70
B:7.34 to 7.66
C:5.69 to 9.31
D:5.34 to 9.66
答案: 【7.34 to 7.66
】

6、选择题:

A researcher wants to estimate the proportion of the population which possess a given characteristic. A random sample of size 600 is taken resulting in 330 items which possess the characteristic. The point estimate for this population proportion is _______.

选项：
A:0.45
B:0.33
C:0.60
D:

0.55

答案: 【

0.55

】
7、选择题:

The t-distribution is similar to a normal distribution. However the t-distribution is _______.

选项：
A:not symmetric
B:discrete
C:bimodal
D:flatter
答案: 【flatter
】

8、选择题:

In order to find values in the t- distribution table, you must convert the sample size or sizes to _______.

选项：
A:population sizes
B:student values
C:z-values
D:degrees of freedom
答案: 【degrees of freedom
】

9、选择题:

If the degrees of freedom in a t-distribution become very large, _______.

选项：
A:the sample mean approaches zero
B:the population size must be very large
C:the t-values and the z-values are almost the same
D:the sample size must be very small
答案: 【the t-values and the z-values are almost the same
】

10、选择题:

In finding a confidence interval for the population mean, the population standard deviation should be used if it is known. If the population standard deviation is not known, then it should be estimated with _______.

选项：
A:the sample variance
B:the range
C:the mean
D:the sample standard deviation
答案: 【the sample standard deviation
】

第九章 章节测试

1、选择题:

The first step in testing a hypothesis is to establish _______.
选项：
A:a not rejectance hypothesis and a rejection hypothesis
B:an indirect hypothesis
C:a power function
D:a null hypothesis and alternative hypothesis
答案: 【a null hypothesis and alternative hypothesis
】

2、选择题:

Consider the following null and alternative hypotheses.

Ho:  m  <=7

Ha:  m > 6

These hypotheses _______________.

选项：
A:are established correctly
B:are not collectively exhaustive
C:are not mutually exclusive
D:do not reference a population parameter
答案: 【are not mutually exclusive
】

3、选择题:

Consider the following null and alternative hypotheses.
Ho: m >= 7
Ha: m < 6

These hypotheses _______________.
选项：
A:are established correctly
B:are not collectively exhaustive
C:are not mutually exclusive
D:do not reference a population parameter
答案: 【are not collectively exhaustive
】

4、选择题:

Consider the following null and alternative hypotheses.

Ho:  £ 352
Ha:  > 352

These hypotheses _______________.

选项：
A:are not mutually exclusive
B:do not reference a population parameter
C:are not collectively exhaustive
D:are established correctly
答案: 【do not reference a population parameter
】

5、选择题:

The region of the distribution in hypothesis testing in which the null hypothesis is rejected is called the _______.

选项：
A:alternative region
B:not rejectance region
C:rejection region
D:null region
答案: 【rejection region
】

6、选择题:

The rejection and not rejectance regions are divided by a point called the _______.

选项：
A:not rejectance value
B:rejection value
C:critical value
D:dividing point
答案: 【critical value
】

7、选择题:

The probability of committing a Type II error is represented by _______.

选项：
A:1 – a
B:a
C:b
D:a / 2
答案: 【b
】

8、选择题:

Jennifer Cantu, Customer Services Manager at Tri-Nation Auto Insurance, monitors the claims processing time of the claims division. Her standard includes ‘a mean processing time of 5 days or less’. Each week, her staff checks for compliance by analysing a random sample of 60 claims. Jennifer’s alternative hypothesis is ________.

选项：
A:< 5
B:n = 60
C:> 5
D:5
答案: 【> 5
】

9、选择题:

The manufacturers of a deodorant claim that the mean drying time of their product is, at most, 15 minutes. A sample consisting of 16 cans of the product was used to test the manufacturer’s claim. The experiment yielded a mean drying time of 18 minutes with a standard deviation of 6 minutes. Test the claim at the 0.05 significance level.

选项：
A:Computed test statistic = 2 and is greater than 2.131, so reject H₀: µ ≤ 15.
B:Computed test statistic = 2 and is greater than 1.645, so reject H₀: µ ≤ 15.
C:Computed test statistic = 2 and is greater than 1.96, so reject H₀: µ ≤ 15.
D:Computed test statistic = 2 and is greater than 1.753, so reject H₀: µ = 15.
答案: 【Computed test statistic = 2 and is greater than 1.753, so reject H₀: µ = 15.
】

10、选择题:

What happens to the rejection region if the level of significance is changed from 0.10 to 0.05?
选项：
A:it gets larger
B:it gets smaller
C:it does not change
答案: 【it gets smaller
】

第十章 章节测试

1、选择题:

Restaurateur, Daniel Valentine, is evaluating two sites, Port Douglas and Mission Beach, for his next restaurant. He wants to prove that Port Douglas residents (population 1) dine out more often than Mission Beach residents (population 2). Denny plans to test this hypothesis using a random sample of 81 families from each town. His null hypothesis is __________.

选项：
A:m₁ – m₂ > 0
B:p₁ – p₂ = 0
C:m₁ ≤m₂ 
D:s₁² < s₂²
答案: 【m₁ ≤m₂ 
】

2、选择题:

A researcher wants to estimate the difference in the means of two populations. A random sample of 36 items from the first population results in a sample mean of 430. A random sample of 49 items from the second population results in a sample mean of 460. The population standard deviations are 120 for the first population and 140 for the second population. From this information, a point estimate of the difference of population means can be calculated as _______.

选项：
A:46
B:-30
C:-13
D:43
答案: 【-30
】

3、选择题:

A researcher wants to estimate the difference in the means of two populations. A random sample of 36 items from the first population results in a sample mean of 430. A random sample of 49 items from the second population results in a sample mean of 460. The population standard deviations are 120 for the first population and 140 for the second population. From this information, a 95% confidence interval for the difference in population means is _______.

选项：
A:–95.90 to 35.90
B:85.44 to 25.44
C:–76.53 to 16.53
D:–102.83 to 42.43
答案: 【85.44 to 25.44
】

4、选择题:

A researcher is interested in testing to determine if the mean of population one is greater than the mean of population two. The null hypothesis is that there is no difference in the population means (i.e. the difference is zero). The alternative hypothesis is that there is a difference (i.e. the difference is not equal to zero). He randomly selects a sample of 9 items from population one resulting in a mean of 14.3 and a standard deviation of 3.4. He randomly selects a sample of 14 items from population two resulting in a mean of 11.8 and a standard deviation 2.9. He is using an alpha value of .10 to conduct this test. Assuming that the populations are normally distributed, the degrees of freedom for this problem are _______.

选项：
A:22
B:15
C:23
D:2
答案: 【15】

5、选择题:

A researcher wants to conduct a before/after study on 11 subjects to determine if a treatment results in any difference in scores. The null hypothesis is that the average difference is zero while the alternative hypothesis is that the average difference is not zero. Scores are obtained on the subjects both before and after the treatment. After subtracting the after scores from the before scores, the average difference is calculated to be –2.40 with a sample standard deviation of 1.21. Assume that the differences are normally distributed in the population. The degrees of freedom for this test are _______.

选项：
A:10
B:20
C:11
D:9
答案: 【10】

6、选择题:

A researcher is performing a two-tailed related samples (matched pairs) t-test. A total of 12 people are in the sample, and before and after measures are taken. The observed t-value for this is –1.84. The level of significance is 0.05. The correct decision is to _______.

选项：
A:do not reject the null hypothesis
B:reject the null hypothesis
C:take a larger sample
D:use the z-table instead of the t-table
答案: 【do not reject the null hypothesis
】

7、选择题:

Stefan Irwin, Marketing Manager at Classic Merchandise, is investigating response rates to scented and unscented direct mail catalogues. If the response rate for the scented catalogue (population 1) is higher, Mike will adopt the scented version. His staff randomly selects two samples of 200 each from the company’s customer database. One month after the 400 test catalogues were mailed, forty-five orders (twenty-five from the scented and twenty from the unscented) were received from the test catalogues. Assuming a  = .01, Mike’s alternate hypothesis is ________________.

选项：
A:p₁ – p₂ > 0
B:m₁ – m₂ = 0
C:m₁ – μ₂ ≠ 0
D:s₁² < s₂²
答案: 【p₁ – p₂ > 0
】

8、选择题:

Cowra Construction Company purchases steel rods for its projects. Based on previous tests, Clarrie Carter, Quality Assurance Manager, has recommended purchasing rods from Redding Rods (population 1), rather than Stockton Steel (population 2), since Redding’s rods had less variability in length. Recently, Stockton revised it rod shearing operation, and Clarrie has sampled the outputs from Redding’s and Stockton’s rod manufacturing processes. The results for Redding were s₁² = 0.10 with n₁ = 8, and, for Stockton, the results were s₂² = 0.05 with n₂ = 10. Assume that rod lengths are normally distributed in the population. Clarrie’s alternate hypothesis is __________________.

选项：
A:s₁²  = s₂²
B:s₁² > s₂²
C:s₁² < s₂²
D:s₁² ≠ s₂²
答案: 【s₁² > s₂²
】

9、选择题:

Tamara Hill, Fund Manager with Hillcrest Value Fund, manages a portfolio of 250 common stocks. Tamara is searching for a ‘low risk’ issue to add to the portfolio, i.e. one with a price variance less than that of the S&P 500 index. Moreover, she assumes an issue is not ‘low risk’ until demonstrated otherwise. Her staff reported that during the last nine quarters the price variance for the S&P 500 index (population 1) was 25, and for the last seven quarters the price variance for XYC common (population 2) was 8. Assume that stock prices are normally distributed in the population. Using a = 0.05, the appropriate decision is _______.

选项：
A:do not reject the null hypothesis s₁²  ¹  s₂²
B:eject the null hypothesis s₁²  ¹  s₂²
C:reject the null hypothesis s₁²  =  s₂²
D:do not reject the null hypothesis s₁²  =  s₂²
答案: 【do not reject the null hypothesis s₁²  =  s₂²
】

10、选择题:

Cindy Ho, Finance Manager at Red Hill Radiator Supplies (RHRS), theorises that the discount level offered to credit customers affects the average collection period on credit sales. Accordingly, she has designed an experiment to test her theory using four sales discount rates (0%, 2%, 4% and 6%) by randomly assigning five customers to each sales discount rate. An analysis of Cindy’s data produced the following ANOVA table.

Using a = 0.01, the appropriate decision is _________.
选项：
A:do not reject the null hypothesis m1 = m2 = m3 = m4
B:reject the null hypothesis m1 ≠ m2 ≠ m3 ≠ m4
C:do not reject the null hypothesis m1 ≠ m2 ≠ m3 ≠m4
D:reject the null hypothesis m1 = m2 = m3 = m4
答案: 【do not reject the null hypothesis m1 = m2 = m3 = m4
】

第十一章 章节测试

1、选择题:

For the same set of observations on a specified dependent variable, two different

independent variables were used to develop 2 simple linear regression models.

The results are summarized as follows:

Based on the above results, we can conclude that
选项：
A:the SSE for Model II is smaller than the SSE for Model I.
B:a prediction based on Model II is likely better than a prediction based on Model I.
C:a prediction based on Model I is likely better than a prediction based on Model II.
D:the total variation is different for Model I and Model II.
答案: 【a prediction based on Model I is likely better than a prediction based on Model II.
】

2、选择题:

A regression analysis between sales (in $1000) and advertising (in $100) yielded the least

squares line = 75 + 6x.  This implies that if $800 is spent on advertising, then the

predicted amount of sales (in dollars) is
选项：
A:$4,875
B:$487,500
C:$123,000
D:$12,300
答案: 【$123,000
】

3、选择题:

The following results were obtained from a simple regression analysis:

= 37.2895 – 1.2024x

r² = 0.6744 and s² = 0.2934

For each unit change in x, the estimated change in the average value of y is equal to
选项：
A:0.6744
B:37.289
C:0.2934
D:-1.2024
答案: 【-1.2024
】

4、选择题:

A regression analysis between sales (in $1,000) and advertising (in $) yielded the least square line

= 80,000 + 5x

This implies that an
选项：
A:increase of $1 in advertising is expected to result in an increase of $5,000 in sales.
B:increase of $1 in advertising is expected to result in an increase of $5 in sales.
C:increase of $5 in advertising is expected to result in an increase of $5,000 in sales.
D:increase of $1 in advertising is expected to result in an increase of $80,005 in sales.
答案: 【increase of $1 in advertising is expected to result in an increase of $5,000 in sales.
】

5、选择题:

The point estimate of the variance of the error term in a regression model is
选项：
A:SSE
B:
C:
D:MSE
答案: 【MSE
】

6、选择题:

In a regression problem, if the coefficient of determination is 0.95, this means that:
选项：
A:95% of the variation in x can be explained by the variation in y.
B:95% of the y values are positive.
C:95% of the variation in y can be explained by the variation in x.
D:95% of the x values are equal.
答案: 【95% of the variation in y can be explained by the variation in x.
】

7、选择题:

In regression analysis, the residuals represent the:
选项：
A:change in y per unit change in x.
B:difference between the actual y values and their predicted values.
C:square root of the coefficient of determination.
D:difference between the actual x values and their predicted values.
答案: 【difference between the actual y values and their predicted values.
】

8、选择题:

In the simple linear regression model, the population parameters of the y-intercept and the slope are estimated by:
选项：
A: and

 
B: and
 
C: and 
 
D: and
 
答案: 【 and
 
】
9、选择题:

If the standard error of estimate  = 20 and n = 10, then the sum of squares for error, SSE, is:
选项：
A:400
B:3200
C:40，000
D:4000
答案: 【3200】

10、选择题:

Which of the following statistics and procedures can be used to determine whether a linear model should be employed?
选项：
A:The standard error of estimate.
B:All of the above are correct answers.
C:The t-test of the slope.
D:The coefficient of determination.
答案: 【All of the above are correct answers.
】[/$]