New Semester
Started
Get
50% OFF
Study Help!
--h --m --s
Claim Now
Question Answers
Textbooks
Find textbooks, questions and answers
Oops, something went wrong!
Change your search query and then try again
S
Books
FREE
Study Help
Expert Questions
Accounting
General Management
Mathematics
Finance
Organizational Behaviour
Law
Physics
Operating System
Management Leadership
Sociology
Programming
Marketing
Database
Computer Network
Economics
Textbooks Solutions
Accounting
Managerial Accounting
Management Leadership
Cost Accounting
Statistics
Business Law
Corporate Finance
Finance
Economics
Auditing
Tutors
Online Tutors
Find a Tutor
Hire a Tutor
Become a Tutor
AI Tutor
AI Study Planner
NEW
Sell Books
Search
Search
Sign In
Register
study help
business
business statistics communicating
Introduction To The Practice Of Statistics 6th Edition David S. Moore, George P. McCabe, Bruce A. Craig - Solutions
A corporate liability trial. A major court case on the health effects of drinking contaminated water took place in the town of Woburn, Massachusetts.A town well in Woburn was contaminated by industrial chemicals. During the period that residents drank water from this well, there were 16 birth
CH ALLENGE Calculating sample sizes for the twosample problem. For a single proportion the margin of error of a confidence interval is largest for any given sample size n and confidence level C when ˆp = 0.5. This led us to use p∗ = 0.5 for planning purposes. The same kind of result is true for
CH ALLENGE Sample size and the margin of error. In the first section of this chapter, we studied the effect of the sample size on the margin of error of the confidence interval for a single proportion.In this exercise we perform some calculations to observe this effect for the two-sample
CH ALLENGE Sample size and the P-value. In this exercise we examine the effect of the sample size on the significance test for comparing two proportions. In each case suppose that ˆp1 = 0.5 andˆp2 = 0.4, and take n to be the common value of n1 and n2. Use the z statistic to test H0: p1 = p2
Parental pressure and gender. The Pew Research Center poll in Exercise 8.69 (page 521) also reported that 62% of the men and 51% of the women thought parents are placing too little pressure on their children to succeed in school. Assuming that the respondents were 52% women, compare the proportions
Gallup Poll study. Go to the Gallup Poll Web site http://www.galluppoll.com/ and find a poll that has several questions of interest to you. Summarize the results of the poll giving margins of error and comparisons of interest. (For this exercise, you may assume that the data come from an SRS.)
CHALLENGE Changing majors during college. In a random sample of 975 students from a large public university, it was found that 463 of the students changed majors during their college years.(a) Give a 95% confidence interval for the proportion of students at this university who change majors.(b)
CHALLENGE Even more on gender bias in textbooks.Refer to the previous exercise. Let us now combine the categories “girl” with “woman”and “boy” with “man.” For each text calculate the proportion of male references and test the hypothesis that male and female references are equally
CHALLENGE More on gender bias in textbooks. Refer to the study of gender bias and stereotyping described in Exercise 8.53 (page 519). Here are the counts of “girl,” “woman,” “boy,” and “man” for all of the syntax texts studied. The one we analyzed in Exercise 8.53 was number 6.Text
Brand loyalty in action. The study mentioned in the previous exercise found that two-thirds of the die-hard fans attended Cubs games at least once a month, but only 20% of the less loyal fans attended this often. Analyze these data using a significance test and a confidence interval. Write a short
Brand loyalty and the Chicago Cubs. According to literature on brand loyalty, consumers who are loyal to a brand are likely to consistently select the same product. This type of consistency could come from a positive childhood association. To examine brand loyalty among fans of the Chicago Cubs,
Parental pressure to succeed in school. A Pew Research Center Poll used telephone interviews to ask American adults if parents are pushing their kids too hard to succeed in school. Of those responding, 56% said parents are placing too little pressure on their children.33 Assuming that this is an
Improving the time to repair golf clubs. The Ping Company makes custom-built golf clubs and competes in the $4 billion golf equipment industry.To improve its business processes, Ping decided to seek ISO 9001 certification.32 As part of this process, a study of the time it took to repair golf clubs
Nonresponse for the income question. Refer to the previous two exercises. Give the total number of users and the total number of nonusers for the analysis of education. Do the same for the analysis of income. The difference is due to respondents who chose “Rather not say” for the income
Income of the customers. The study mentioned in the previous exercise also asked about income.Among Internet users, 493 reported income of less than $50,000 and 378 reported income of$50,000 or more. (Not everyone answered the income question.) The corresponding numbers for nonusers were 477 and
Education of the customers. To devise effective marketing strategies it is helpful to know the characteristics of your customers. A study compared demographic characteristics of people who use the Internet for travel arrangements and of people who do not.31 Of 1132 Internet users, 643 had completed
“No Sweat” garment labels. Following complaints about the working conditions in some apparel factories both in the United States and abroad, a joint government and industry commission recommended in 1998 that companies that monitor and enforce proper standards be allowed to display a “No
CHALLENGE More on the effects of reducing air pollution. In Exercise 8.48 the effects of a reduction in air pollution on wheezing was examined by comparing the one-year change in symptoms in a group of residents who lived on congested streets with a group who lived in an area that had been
CHALLENGE Cell phone ownership: 2000 versus 2004.Refer to Exercise 8.41 (page 517). The estimated proportion of undergraduates owning a phone in 2000 was 43%. We want to test whether the proportion of undergraduate cell phone owners has more than doubled in the last 4 years.(a) Compute the quantity
CHALLENGE Proportion of male heavy lottery players.A study of state lotteries included a random digit dialing (RDD) survey conducted by the National Opinion Research Center (NORC). The survey asked 2406 adults about their lottery spending.29 A total of 248 individuals were classified as “heavy”
CHALLENG E Even more on downloading music from the Internet. The following quotation is from a recent survey of Internet users. The sample size for the survey was 1371. Since 18% of those surveyed said they download music, the sample size for this subsample is 247.Among current music downloaders,
Gender and using a handheld phone while driving. Refer to the previous exercise. In this same report, this percent was broken down into 59% for men and 56% for women. Assuming that, among the 1048 respondents, there were an equal number of men and women, construct a 95% confidence interval for the
Using a handheld phone while driving. Refer to Exercise 8.14 (page 503). This same poll found that 58% of the respondents talked on a handheld phone while driving in the last year. Construct a 90% confidence interval for the proportion of U.S.drivers who talked on a handheld phone while driving in
What’s wrong? For each of the following, explain what is wrong and why.(a) A 90% confidence interval for the difference in two proportions includes errors due to nonresponse.(b) A z statistic is used to test the null hypothesis that H0 : ˆp1 = ˆp2.(c) If two sample proportions are equal, then
Pet ownership and marital status: the significance test. In Exercise 8.45 (page 517)we compared the proportion of pet owners who were married with the proportion of non–pet owners who were married in the Health ABC Study.Use a significance test to make the comparison and summarize the results of
Pet ownership and gender: the significance test. In Exercise 8.44 (page 517) we compared the proportion of pet owners who were women with the proportion of non–pet owners who were women in the Health ABC Study. Use a significance test to make the comparison and summarize the results of your
CH ALLENGE Bicycle accidents, alcohol, and gender. In Exercise 8.28 (page 504) we examined the percent of fatally injured bicyclists tested for alcohol who tested positive. Here we examine the same data with respect to gender.Gender n X(tested positive)Female 191 27 Male 1520 515(a) Summarize the
Gender bias in textbooks. To what extent do syntax textbooks, which analyze the structure of sentences, illustrate gender bias? A study of this question sampled sentences from 10 texts.27 One part of the study examined the use of the words“girl,” “boy,” “man,” and “woman.” We will
Cheating during a test: 2002 versus 2004. In Exercise 8.16, you examined the proportion of high school students who cheated on tests at least twice during the past year. Included in that study were the results for both 2002 and 2004. A reported 9054 out of 24,142 students said they cheated at least
Who gets stock options? Different kinds of companies compensate their key employees in different ways. Established companies may pay higher salaries, while new companies may offer stock options that will be valuable if the company succeeds. Do high-tech companies tend to offer stock options more
More on downloading music from the Internet.Refer to the previous exercise. Suppose we are not exactly sure about the sizes of the samples.Redo the calculations for the significance test and the confidence interval under the following assumptions: (i) both sample sizes are 1000, (ii) both sample
Downloading music from the Internet. A 2005 survey of Internet users reported that 22%downloaded music onto their computers. The filing of lawsuits by the recording industry may be a reason why this percent has decreased from the estimate of 29% from a survey taken two years before.25 Assume that
Effects of reducing air pollution. A study that evaluated the effects of a reduction in exposure to traffic-related air pollutants compared respiratory symptoms of 283 residents of an area with congested streets with 165 residents in a similar area where the congestion was removed because a bypass
A comparison of the proportion of frequent binge drinkers, revisited. Refer to Exercise 8.46.Redo the exercise in terms of the proportion of nonfrequent binge drinkers in each classification.Explain how you could have obtained these results from the calculations you did in Exercise 8.46.
A comparison of the proportion of frequent binge drinkers. In the published report on binge drinking that we used for Example 8.1, survey results from both 1993 and 1999 are presented.Using the table below, test whether the proportions of frequent binge drinkers are different at the 5%level. Also
Pet ownership and marital status. Refer to the previous exercise. The 595 pet owners and 1939 non–pet owners were also classified according to whether or not they were married. For the pet owners, 53.3% were married, while for the non–pet owners, 57.7% were married. Find a 95% confidence
Pet ownership and gender. In the Health ABC Study, 595 subjects owned a pet and 1939 subjects did not.23 Among the pet owners, there were 285 women; 1024 of the non–pet owners were women.Find the proportion of pet owners who were women.Do the same for the non–pet owners. Give a 95%confidence
CHALLENGE Gender and gambling behaviors among student-athletes. Gambling behaviors of Division I intercollegiate student-athletes were analyzed in Exercises 8.11 and 8.12 (page 502). Use the methods of this section to compare the males and females with a significance test, and give an estimate of
ˆp1 − ˆp2 and the Normal distribution. Suppose there are two binomial populations. For the first, the true proportion of successes is 0.3; for the second, it is 0.4. Consider taking independent samples from these populations, 50 from the first and 60 from the second.(a) Find the mean and the
Comparing cell phone ownership in 2003 and 2004. In Exercise 8.4 (page 497), you were asked to compare the 2004 proportion of cell phone owners (89%) with the 2003 estimate (83%). It would be more appropriate to compare these two proportions using the methods of this section. Given that the sample
More on whether to use the large-sample confidence interval. In each of the following circumstances state whether you would use the large-sample confidence interval.(a) n1 = 25, n2 = 25, X1 = 12, and X2 = 8.(b) n1 = 25, n2 = 25, X1 = 17, and X2 = 12.(c) n1 = 60, n2 = 30, X1 = 30, and X2 = 15.(d) n1
Can we use the large-sample confidence interval?In each of the following circumstances state whether you would use the large-sample confidence interval.(a) n1 = 30, n2 = 30, X1 = 10, and X2 = 15.(b) n1 = 15, n2 = 10, X1 = 10, and X2 = 5.(c) n1 = 25, n2 = 20, X1 = 11, and X2 = 8.(d) n1 = 40, n2 =
Changing the alternative hypothesis. Refer to the previous exercise.Does your conclusion change if you test whether the proportion of men that favor Commercial A is larger than the proportion of females?Explain.
(page 509). Test that the proportions of women and men that liked Commercial A are the same versus the two-sided alternative at the 5% level.
Gender and commercial preference: the z test. Refer to Exercise
Gender and commercial preference, revisited. Refer to Exercise 8.35. Construct a 95% confidence interval for the difference in proportions that favor Commercial B. Explain how you could have obtained these results from the calculations you did in Exercise 8.35.
Gender and commercial preference. A study was designed to compare two energy drink commercials. Each participant was shown the commercials in random order and asked to select the better one. Commercial A was selected by 45 out of 100 women and 80 out of 140 men.Give an estimate of the difference in
Are the customers dissatisfied? An automobile manufacturer would like to know what proportion of its customers are dissatisfied with the service received from their local dealer. The customer relations department will survey a random sample of customers and compute a 95% confidence interval for the
CHALLENGE Sample size needed for an evaluation, continued. The evaluation in the previous exercise will also have questions that have not been asked before, so you do not have previous information about the possible value of p. Repeat the calculation above for the following values of p∗: 0.1,
Sample size needed for an evaluation. You are planning an evaluation of a semester-long alcohol awareness campaign at your college. Previous evaluations indicate that about 25% of the students surveyed will respond “Yes” to the question “Did the campaign alter your behavior toward alcohol
More information is needed. Refer to the previous exercise. Suppose that after reviewing the results of the previous survey, you proceeded with preliminary development of the product. Now you are at the stage where you need to decide whether or not to make a major investment to produce and market
Is there interest in a new product? One of your employees has suggested that your company develop a new product. You decide to take a random sample of your customers and ask whether or not there is interest in the new product. The response is on a 1 to 5 scale with 1 indicating “definitely would
Tossing a coin 10,000 times! The South African mathematician John Kerrich, while a prisoner of war during World War II, tossed a coin 10,000 times and obtained 5067 heads.(a) Is this significant evidence at the 5% level that the probability that Kerrich’s coin comes up heads is not 0.5? Use a
CHALLENGE Bicycle accidents and alcohol. In the United States approximately 900 people die in bicycle accidents each year. One study examined the records of 1711 bicyclists aged 15 or older who were fatally injured in bicycle accidents between 1987 and 1991 and were tested for alcohol. Of these,
Dogs sniffing out cancer. A 2005 study by researchers set out to determine whether dogs could be trained to detect lung and breast cancer by sniffing exhaled breath samples.19 For the breast cancer portion, breath samples from 6 cancer patients and 17 cancer-free volunteers were used.Each dog had
CHALLENGE Annual income of older adults. In the study described in the previous exercise, 1434 subjects out of a total of 2533 reported that their annual income was $25,000 or more.(a) Give a 95% confidence interval for the true proportion of subjects in this population with incomes of at least
Pet ownership among older adults. In a study of the relationship between pet ownership and physical activity in older adults,18 594 subjects reported that they owned a pet, while 1939 reported that they did not. Give a 95% confidence interval for the proportion of older adults in this population
High school students and dieting. In the study described in the previous exercise, the researchers also surveyed 266 high school students who were 18 years old. In this sample 58.3% reported that they had dieted sometime in the past year. Give a 95% confidence interval for the true proportion of
College students and dieting. For a study of unhealthy eating behaviors, 267 college women aged 18 to 25 years were surveyed.17 Of these, 69%reported that they had been on a diet sometime during the past year. Give a 95% confidence interval for the true proportion of college women aged 18 to 25
Instant versus fresh-brewed coffee. A matched pairs experiment compares the taste of instant versus fresh-brewed coffee. Each subject tastes two unmarked cups of coffee, one of each type, in random order and states which he or she prefers.Of the 40 subjects who participate in the study, 12 prefer
Can we use the z test? In each of the following cases state whether or not the Normal approximation to the binomial should be used for a significance test on the population proportion p.(a) n = 30 and H0: p = 0.2.(b) n = 30 and H0: p = 0.6.(c) n = 100 and H0: p = 0.5.(d) n = 200 and H0: p = 0.01.
More on confidence level and interval width.Refer to Exercise 8.19. Would a 99% confidence interval be wider or narrower than the one that you found in that exercise? Verify your results by computing the interval.
Student loans larger than $30,000. A survey of 1280 student loan borrowers found that 192 had loans totaling more than $30,000 for their undergraduate education.16 Give a 95% confidence interval for the proportion of all student loan borrowers who have loans of more than $30,000 for their
Confidence level and interval width. Refer to Exercise 8.17. Would a 90% confidence interval be wider or narrower than the one that you found in that exercise? Verify your results by computing the interval.
CHALLENGE Long sermons. The National Congregations Study collected data in a one-hour interview with a key informant—that is, a minister, priest, rabbi, or other staff person or leader.15 One question asked concerned the length of the typical sermon.For this question 390 out of 1191 congregations
Cheating during a test. A national survey of high school students conducted by the Josephson Institute of Ethics was sent to 37,328 students, and 24,142 were returned. One question asked students if they had cheated during a test in the last school year.14 Of those who returned the survey, 9054
Getting angry at other drivers. Refer to Exercise 8.14. The same Pew Poll found that 38% of the respondents “shouted, cursed or made gestures to other drivers” in the last year.(a) Construct a 95% confidence interval for the true proportion of U.S. drivers who did these actions in the last
Do you enjoy driving your car? The Pew Research Center recently polled n = 1048 U.S. drivers and found that 69% enjoyed driving their automobiles.13(a) Construct a 95% confidence interval for the proportion of U.S. drivers who enjoy driving their automobiles.(b) In 1991, a Gallup Poll reported this
Do students report Internet sources? The National Survey of Student Engagement found that 87% of students report that their peers at least“sometimes” copy information from the Internet in their papers without reporting the source.12 Assume that the sample size is 430,000.(a) Find the margin of
Gambling and female athletes. In the study described in the previous exercise, 1447 out of a total of 3469 female student-athletes reported participation in some gambling activity.(a) Use the large-sample methods to find an estimate of the true proportion with a 95% confidence interval.(b) The
Gambling and college athletics. Gambling is an issue of great concern to those involved in intercollegiate athletics. Because of this, the National Collegiate Athletic Association (NCAA)surveyed student-athletes concerning their gambling-related behaviors.11 There were 5594 Division I male athletes
ˆp and the Normal distribution. Consider the binomial setting with n = 60 and p = 0.4.(a) The sample proportion ˆp will have a distribution that is approximately Normal. Give the mean and the standard deviation of this Normal distribution.(b) Draw a sketch of this Normal distribution. Mark the
What’s wrong? Explain what is wrong with each of the following:(a) An approximate 99% confidence interval for an unknown proportion p is ˆp plus or minus its standard error.(b) When performing a large-sample significance test for a population proportion, the t distribution is used to compute the
More on whether to use the large-sample confidence interval. In each of the following circumstances state whether you would use the large-sample confidence interval.(a) n = 8, X = 4.(b) n = 500, X = 13.(c) n = 40, X = 18.(d) n = 15, X = 15.(e) n = 50, X = 22.
Can we use the large-sample confidence interval?In each of the following circumstances state whether you would use the large-sample confidence interval.(a) n = 50, X = 30.(b) n = 90, X = 15.(c) n = 10, X = 2.(d) n = 60, X = 50.(e) n = 25, X = 15.
Calculating the sample size. Refer to Exercise 8.3 (page 497). You plan to do a larger survey such that the 95% margin of error is no larger than 0.02. Using the results from the small survey of 100 students, what sample size would you use?
Confidence level and sample size. Refer to Example 8.6 (page 499).Suppose the university was interested in a 90% confidence interval with margin of error 0.03. Would the required sample size be smaller or larger than 1068 students? Verify this by performing the calculation.
Owning a cell phone, continued. Refer to Exercise 8.1 (page 490).It was reported that cell phone ownership by undergraduate students in 2003 was 83%. Do the sample data in 2004 give good evidence that this percent has increased?(a) Give the null and alternative hypotheses.(b) Carry out the
Working while enrolled in school. A 1993 nationwide survey by the National Center for Education Statistics reports that 72% of all undergraduates work while enrolled in school.9 You decide to test whether this percent is different at your university. In your random sample of 100 students, 77 said
Importance of cell phone “features and functions.” In that same survey, one question asked what aspect was most important when buying a cell phone. “Features and functions” was the choice for 336 students. Give a 95% confidence interval for the proportion of U.S.students who find
Owning a cell phone. In a 2004 survey of 1200 undergraduate students throughout the United States, 89% of the respondents said they owned a cell phone.5 For 90% confidence, what is the margin of error?
CHALLENGE More on house prices. Go to the Web site www.realtor.com and select two geographical areas of interest to you. You will compare the prices of similar types of homes in these two areas. State clearly how you define the areas and the type of homes. For example, you can use city names or zip
CHALL ENGE House prices. How much more would you expect to pay for a home that has four bedrooms than for a home that has three? Here are some data forWest Lafayette, Indiana.39 These are the asking prices (in dollars) that the owners have set for their homes.Four-bedroom homes:121,900 139,900
Sample size calculation (optional).Example 7.13 (page 449) tells us that the mean height of 10-year-old girls is N(56.4, 2.7) and for boys it is N(55.7, 3.8). The null hypothesis that the mean heights of 10-year-old boys and girls are equal is clearly false. The difference in mean heights is 56.4
Different methods of teaching reading. In the READING data set, described in the Data Appendix, the response variable Post3 is to be compared for three methods of teaching reading.The Basal method is the standard, or control, method, and the two new methods are DRTA and Strat. We can use the
CH ALLENGE Male and female CS students (optional).Is there a difference between the average SAT scores of males and females? The CSDATA data set, described in the Data Appendix, gives the Math (SATM) and Verbal (SATV) scores for a group of 224 computer science majors. The variable SEX indicates
CH ALLENGE More on using the complete CRP data set. Refer to the previous exercise. The researchers in this study also measured α1-acid glycoprotein (AGP). This protein is similar to CRP in that it is an indicator of infection. However, it rises more slowly than CRP and reaches a maximum 2 to 3
CH ALLENGE Inference using the complete CRP data set. In Exercise 7.26 (page 442) you analyzed the C-reactive protein (CRP) scores for a random sample of 40 children who participated in a study in Papua New Guinea. Serum retinol for the same children was analyzed in Exercise 7.28.Data for all 90
CH ALLENGE PCBs in fish, continued. Refer to the previous exercise. Not all types of PCBs are equally harmful. A scale has been developed to convert the raw amount of each type of PCB to a toxic equivalent (TEQ). The PCB data set contains a variable TEQPCB that is the total TEQ from all PCBs found
CHALLENGE PCBs in fish. Polychlorinated biphenyls(PCBs) are a collection of compounds that are no longer produced in the United States but are still found in the environment. Evidence suggests that they can cause harmful health effects when consumed. Because PCBs can accumulate in fish, efforts
More on conditions for inference. Table 1.2(page 10) gives literacy rates for men and women in 17 Islamic nations. Is it proper to apply the one-sample t method to these data to give a 95%confidence interval for the mean literacy rate of Islamic men? Explain your answer.
Conditions for inference. The report cited in Exercise 7.130 says that the distribution of alcohol consumption among the individuals studied is“grossly skew.”(a) Do you think that this skewness prevents the use of the two-sample t test for equality of means?Explain your answer.(b) (Optional) Do
Occupation and diet, continued (optional). Use of the pooled two-sample t test is justified in part(b) of the previous exercise. Explain why. Find the P-value for the pooled t statistic, and compare with your result in the previous exercise.
Occupation and diet. Do various occupational groups differ in their diets? A British study of this question compared 98 drivers and 83 conductors of London double-decker buses.38 The conductors’jobs require more physical activity. The article reporting the study gives the data as “Mean daily
Behavior of pet owners. On the morning of March 5, 1996, a train with 14 tankers of propane derailed near the center of the small Wisconsin town of Weyauwega. Six of the tankers were ruptured and burning when the 1700 residents were ordered to evacuate the town. Researchers study disasters like
CHALL ENGE Self-concept and school performance.Refer to the previous exercise. Although self-concept in this study was measured on a scale with values in the data set ranging from 20 to 80, many prefer to think of this kind of variable as having only two possible values: low self-concept or high
CHALL ENGE Do women perform better in school?Some research suggests that women perform better than men in school but men score higher on standardized tests. Table 1.9 (page 29)presents data on ameasure of school performance, grade point average (GPA), and a standardized test, IQ, for 78
Weight-loss programs. In a study of the effectiveness of weight-loss programs, 47 subjects who were at least 20% overweight took part in a group support program for 10 weeks. Private weighings determined each subject’s weight at the beginning of the program and 6 months after the program’s end.
Competitive prices? A retailer entered into an exclusive agreement with a supplier who guaranteed to provide all products at competitive prices. The retailer eventually began to purchase supplies from other vendors who offered better prices. The original supplier filed a legal action claiming
CHALLENGE Even more on the complete tree size data set. The DBH measures in the LONGLEAF data set do not appear to be Normally distributed. Make a histogram of the data and a Normal quantile plot if you have the software available. Mark the mean and the median on the histogram. Now, transform the
Showing 1300 - 1400
of 6020
First
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Last
Step by Step Answers
Get 50% OFF
Claim Now
