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
probability statistics
The Practice Of Statistics For Business And Economics 3rd Edition David S. Moore, George P. McCabe, Layth C. Alwan, Bruce A. Craig, William M. Duckworth - Solutions
Trends in broadband use over time. The Pew Internet and American Life Project collects data about the impact of the Internet on various aspects of American life.12 One set of surveys has tracked the use of broadband in homes over a period of several years.13 Here are some data on the percent of
Plot the test statistic and the P-values. Here is a 2 × 2 two-way table of counts. The two categorical variables areU and V, and the possible values for each of these variables are 0 and 1.DATADATA DATADATADATA DATADATADATADATADATA DATADATADATADATADATA DATADATADATADATADATA DATADATADATADATADATA
Plot the test statistic and the P-values. Here is a 2 × 2 two-way table of counts. The two categorical variables areU and V, and the possible values for each of these variables are 0 and 1. Notice that the second row depends upon a quantity that we calla. For this exercise you will examine how the
Obesity and health. Recent studies have shown that earlier reports underestimated the health risks associated with being overweight. The error was due to overlooking lurking variables.In particular, smoking tends both to reduce weight and to lead to earlier death. Note that you answered part (a) of
Discrimination? Wabash Tech has two professional schools, business and law. Here are two-way tables of applicants to both schools, categorized by gender and admission decision.(Although these data are made up, similar situations occur in reality.) DATADATA DATADATADATA DATADATADATADATADATA
Nonresponse in a survey. A business school conducted a survey of companies in its state. They mailed a questionnaire to 200 small companies, 200 medium-sized companies, and 200 large companies. The rate of nonresponse is important in deciding how reliable survey results are. Here are the data on
Hiring practices. A company has been accused of age discrimination in hiring for operator positions. Lawyers for both sides look at data on applicants for the past 3 years. They compare hiring rates for applicants younger than 40 years and those 40 years or older. DATADATA DATADATADATA
Trust and honesty in the workplace. The students surveyed in the study described in the previous exercise were also asked whether they thought trust and honesty were essential in business and the workplace. Here are the counts classified by gender: DATADATA DATADATADATA DATADATADATADATADATA
Lying to a teacher. One of the questions in a survey of high school students asked about lying to teachers.11 The table below gives the numbers of students who said that they lied to a teacher at least once during the past year, classified by gender.DATADATA DATADATADATA DATADATADATADATADATA
Exercise and adequate sleep. A survey of 656 boys and girls who were 13 to 18 years old asked about adequate sleep and other health-related behaviors. The recommended amount of sleep is six to eight hours per night.10 In the survey 54% of the respondents reported that they got less than this amount
How does RDC vary across the country? The survey described in the previous exercise also classified community banks by region.9 Here is the 6 × 2 table of counts: DATADATA DATADATADATA DATADATADATADATADATA DATADATADATADATADATA DATADATADATADATADATA DATADATADATADATADATA DATADATADATADATADATA
Remote deposit capture. The Federal Reserve has called remote deposit capture (RDC) “the most important development the (U.S) banking industry has seen in years.” This service allows users to scan checks and to transmit the scanned images to a bank for posting.7 In its annual survey of
No Sweat labels. Sample proportions from Example 9.1 and the two-way table in Example 9.2 (page 494) report the same information in different ways. We saw in Chapter 8 (page 479) that the z statistic for the hypothesis of equal population proportions is z = 3.30 with P < 0.001.(a) Find the
The P-value. A test for association gives X2 = 23.21 with df = 6. How would you report the P-value for this problem? Use Table F in the back of the book. Illustrate your solution with a sketch.
Degrees of freedom. A chi-square significance test is performed to examine the association between two categorical variables in a 6×4 table. What are the degrees of freedom associated with the test statistic?
An alternative view. Refer to Figure 9.1. Verify that you can obtain the expected count for the first cell by multiplying the number of successful firms by the percent of firms that have exclusive territories. Explain your calculations in words.
Expected counts. We want to calculate the expected count of unsuccessful firms that have an exclusive territory. From Figure 9.1, how many firms have exclusive territories? What percent of all firms are unsuccessful? Explain in words why, if there is no association between success and exclusive
Reading software output. Look at Figure 9.1. What percent of firms are successful?What percent of firms had an exclusive-territory contract?
Reading software output. Look at Figure 9.1. What percent of successful firms had an exclusive-territory contract? What percent of unsuccessful firms had an exclusive-territory contract?
A reduction in force. A human resources manager wants to assess the impact of a planned reduction in force (RIF) on employees over the age of 40. (Various laws state that discrimination against this group is illegal.) The company has 800 employees over 40 and 575 who are 40 years of age or less.
Lying and online dating profiles. In Exercise 8.56 (page 476) we analyzed data from a study where it was reported that 22 of 40 men lied about their height in their online profile for a dating Web site. For women, the numbers were 17 out of 40.(a) For these data do you want to consider one of these
Statistics and the law. Casteneda v. Partida is an important court case in which statistical methods were used as part of a legal argument. When reviewing this case, the Supreme Court used the phrase “two or three standard deviations” as a criterion for statistical significance. This Supreme
Students change their majors. In a random sample of 950 students from a large public university, it was found that 444 of the students changed majors during their college years.(a) Give a 99% confidence interval for the proportion of students at this university who change majors.(b) Express your
Unequal sample sizes. You are planning a survey in which a 95% confidence interval for the difference between two proportions will present the results. You will use the conservative guessed value 0.5 for ˆp1 and ˆp2 in your planning. You would like the margin of error of the confidence interval
Choosing sample sizes, continued. As the previous exercise noted, using the guessed value 0.5 for both ˆp1 and ˆp2 gives a conservative margin of error in confidence intervals for the difference between two population proportions. You are planning a survey and will calculate a 95% confidence
Choosing sample sizes. 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. A similar result is true for the two-sample problem. The margin of error of
Howmuch is the improvement? In the setting of the previous exercise, give a 95% confidence interval for the proportion of nonconforming items for the modified process. Then, taking p0 = 0.11 to be the old proportion and p the proportion for the modified process, give a 95% confidence interval for p
Does the new process give a better product? Eleven percent of the products produced by an industrial process over the past several months fail to conform to the specifications. The company modifies the process in an attempt to reduce the rate of nonconformities. In a trial run, the modified process
Use a confidence interval. Use a confidence interval to give an alternative analysis for the previous exercise.8.100 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
Frequent 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.34 A total of 248 individuals were classified as “heavy” players. Of these, 152
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 may come from a positive childhood association.To examine brand loyalty among fans of the Chicago Cubs, 371
The parrot effect: how to increase your tips. An experiment examined the relationship between tips and server behavior in a restaurant.32 In one condition, the server repeated the customer’s order word for word, while in the other condition, the orders were not repeated. Tips were received in 47
Other effects of reducing air pollution. In Exercise 8.92 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 congested but from which
Downloading music from the Internet. The following quote is from a survey of Internet users.31 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, 38% say they are downloading less
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
Gambling and student-athletes. Gambling behaviors of Division I intercollegiate male student-athletes were analyzed in Exercise 8.22 (page 469). Similar data for women were given in Exercise 8.23. Compare the males and females with a significance test and give an estimate of the difference in
Analyze the change in terms of relative risk. Refer to the previous two exercises.(a) Summarize the change data in terms of relative risk. The term“relative risk” is a poor description of the ratio that you are using for this exercise. Give a better term for this ratio.(b) Analyze the data in
Change in wireless only. Refer to the previous exercise.The percent increased to 16.4% in December 2007. Assume the same sample size for this sample.(a) Find the proportion and the count for this sample.(b) Compute the 95% confidence interval for the proportion.(c) Convert the estimate and
Wireless only. Are customers giving up their landlines and relying on wireless for all their phone needs? Surveys have collected data to answer this question.29 In December 2003, 4.2% of households were wireless only. Assume that this survey is based on sampling 15,000 households.(a) Convert the
Too many errors. Refer to the previous exercise. The chance that each of the six intervals that you calculated includes the true proportion for that genre is approximately 95%. In other words, the chance that you make an error and your interval misses the true value is approximately 5%.(a) Explain
Video game genres. U.S. computer and video game software sales were $9.5 billion in 2007.27 A survey of 1102 teens collected data about their video game use. The table below lists the most popular game genres.28 Percent Genre Examples who play Racing NASCAR, Mario Kart, Burnout 74 Puzzle Bejeweled,
Examine the effect of the sample size. Refer to the previous exercise. Assume a variety of different scenarios where the sample size changes but the proportion in the sample who work 10 or more hours a week during the school year remains the same.Write a short report summarizing your results and
Student employment during the school year. A study of 1430 undergraduate students reported that 994 work 10 or more hours a week during the school year. Give a 95% confidence interval for the proportion of all undergraduate students who work 10 or more hours a week during the school year.
We did not know the sample size. Refer to the previous two exercises. We did not report the sample size for the 2000 study, but it is reasonable to assume that it is fairly close to the sample size for the 2004 study.(a) Suppose that the sample size for the 2000 study was only 1000. Redo the
Do the significance test for the change. Refer to the previous exercise. Perform the significance test for comparing the two proportions. Report your test statistic, the P-value, and summarize your conclusion.
Changes in credit card usage by undergraduates. In Exercise 8.30 (page 470) we looked at data from a survey of 1430 undergraduate students and their credit card use. These students were surveyed 2004. In the sample, 43% said that they had four or more credit cards. A similar study performed in 2000
Relative risk for gamers. Refer to the Pew data about gaming on game consoles (Xbox, PlayStation,Wii, etc.) by adults and teens in Exercises 8.66 and 8.67 (page 483). Now, compare the adults with the teens using the relative risk approach.(a) Find the proportion of adult gamers who use game
Effect of the sample size. Return to the study of undergraduate student summer employment described in Exercise 8.76. Similar results from a smaller number of students may not have the same statistical significance. Specifically, suppose that 71 of 78 men surveyed were employed and 62 of 71 women
Is the gender bias statistically significant? The previous exercise addresses a question about gender bias with a confidence interval. Set up the problem as a significance test. Carry out the test and summarize the results.
Gender bias in textbooks. To what extent do textbooks on syntax (analysis of sentence structure) display gender bias? A study of this question sampled sentences from 10 texts.25 One part of the study examined the use of the words “girl,” “boy,”“man,” and “woman.” Call the first two
Summer employment of college students. A university financial aid office polled an SRS of undergraduate students to study their summer employment. Not all students were employed the previous summer. Here are the results for men and women:Men Women Employed 712 623 Not employed 68 92 Total 780
Natural versus artificial Christmas trees. In the Christmas tree survey introduced in Case 8.2 (page 466), respondents who had a tree during the holiday season were asked whether the tree was natural or artificial. Respondents were also asked if they lived in an urban area or in a rural area. Of
A corporate liability trial. A major court case on liability for contamination of groundwater 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 defects
College student summer employment. Suppose (as is roughly true) that 85% of college men and 83% of collegewomen were employed last summer. A sample survey interviews SRSs of 400 college men and 400 college women. The two samples are of course independent.(a) What is the approximate distribution of
What’s wrong? For each of the following, explain what is wrong and why.(a) A z statistic is used to test the null hypothesis that ˆp1 = ˆp2.(b) If two sample proportions are equal, then the sample counts are equal.(c) A 95% confidence interval for the difference in two proportions includes
Draw a picture. Suppose that there are two binomial populations. For the first, the true proportion of successes is 0.4;for the second, it is 0.5. Consider taking independent samples from these populations, 50 from the first and 60 from the second.(a) Find the mean and the standard deviation of the
Can we compare gaming on consoles with gaming on computers? Refer to the previous four exercises. Do you think that you can use the large-sample confidence intervals for a difference in proportions to compare teens’ use of computers with teens’ use of consoles? Write a short paragraph giving
Significance test for gaming on computers. Refer to the previous exercise. Test the null hypothesis that the two proportions are equal. Report the test statistic with the P-value and summarize your conclusion.
Gamers on computers. The report described in Exercise 8.66 also presented data from the same surveys for gaming on computers (desktops or laptops). These devices were used by 73% of adult gamers and by 76% of teen gamers. Answer the questions given in Exercise 8.66 for gaming on computers.
Significance test for gaming on consoles. Refer to the previous exercise. Test the null hypothesis that the two proportions are equal. Report the test statistic with the P-value and summarize your conclusion.
Adult gamers versus teen gamers. APewInternet Project Data Memo presented data comparing adult gamers with teen gamers with respect to the devices on which they play. The data are from two surveys. The adult survey had 1063 gamers, and the teen survey had 1064 gamers. The memo reports that 54% of
Are more Internet users downloading podcasts? Refer to the previous two exercises. The ratio of the proportion in the 2008 sample to the proportion in the 2006 sample is about 2.7.(a) Can you conclude that 2.7 times as many people are downloading podcasts? Explain why or why not.(b) Can you
Significance test for podcast downloading. Refer to the previous exercise. Test the null hypothesis that the two proportions are equal. Report the test statistic with the P-value and summarize your conclusion.
Podcast downloading. The Podcast Alley Web site recently reported that they have 53,501 podcasts available for downloading, with 3,447,545 episodes.21 A Pew survey of Internet users described the results of two surveys about podcast downloading.The first was conducted between February and April
What about weight? Refer to Exercise 8.57 (page 476) for the data on lying about weight. Answer the questions given in the previous exercise for weight.
Do men lie more often about their height thanwomen? Refer to Exercise 8.56(page 476) about lying and online dating profiles.(a) State appropriate null and alternative hypotheses for this setting. Give a justification for your choice.(b) Use the data given in Exercise 8.56 to perform a two-sided
Lying about age. Refer to Exercises 8.56 and 8.57, where you analyzed data about lying about height and weight in online dating profiles. The study also reported that 10 men and 5 women lied about their age.(a) The z confidence interval for comparing two proportions should not be used for these
Gender and labels using plus four. Refer to the previous exercise and to Example 8.7. Suppose that the sample sizes were smaller but that the proportions remained approximately the same. Specifically, assume that 6 out of 30 women were label users and 3 out of 25 men were label users. Compute the
Gender and labels using plus four. Refer to Example 8.7 (page 475), where we computed a 95% confidence interval for the difference in the proportions of men and women who were likely to use “No Sweat” labels when deciding to purchase clothing.Redo the computations using the plus four method and
Lying about weight. The study described in the previous exercise also described results for lying about weight. They reported that 24 men and 23 women lied about their weight. Answer parts (a) through (d) from the previous exercise for these data.
Lying and online dating profiles. JupiterResearch estimates that the U.S. online dating market will reach $932 million by 2011 and that the European online dating sites will double revenues from 243 million euros in 2006 to 549 million euros in 2011.17 When trying to start a new relationship,
Rules for means and variances. It is quite easy to verify the mean and standard deviation of the difference D.(a) What are the means and standard deviations of the two sample proportions ˆp1 and ˆp2? (Look at the box on page 460 if you need to review this.)(b) Use the addition rule for means of
Rules for means and variances. Suppose p1 = 0.4, n1 = 25, p2 = 0.5, n2 = 30. Find the mean and the standard deviation of the sampling distribution of p1 − p2.8.54 Effect of the sample sizes. Suppose p1 = 0.4, n1 = 100, p2 = 0.5, n2 = 120.(a) Find the mean and the standard deviation of the
Justify the cost of the survey. A former editor of the student newspaper agrees to underwrite the study in the previous exercise because she believes the results will demonstrate that most students support an increase in fees. She is willing to provide funds for a sample of size 500. Write a short
Increase student fees? You have been asked to survey students at a large college to determine the proportion that favor an increase in student fees to support an expansion of the student newspaper. Each student will be asked whether he or she is in favor of the proposed increase. Using records
Are the customers dissatisfied? A cell phone manufacturer would like to know what proportion of its customers are dissatisfied with the service received from their local distributor.The customer relations department will survey a random sample of customers and compute a 99% confidence interval for
Start a student nightclub? A student organization wants to start a nightclub for students under the age of 21. To assess support for this proposal, the organization will select an SRS of students and ask each respondent if he or she would patronize this type of establishment. About 75% of the
Change the specs. Refer to the previous exercise. For each of the following variations on the design specifications, state whether the required sample size will be higher, lower, or the same as that found above.(a) Use a 99% confidence interval.(b) Change the allowable margin of error to 0.01.(c)
High-income households on a mailing list. Land’s Beginning sells merchandise through the mail. It is considering buying a list of addresses from a magazine. The magazine claims that at least 25% of its subscribers have high incomes (that is, household income in excess of $100,000). Land’s
Instant versus fresh-brewed coffee. A matched pairs experiment compares the taste of instant coffee with 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 60 subjects who participate in the study, 25
Mathematician tosses 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
Profile of the survey respondents. Of the 500 respondents in the Christmas tree market survey of Case 8.2, 44% had no children at home and 56% had at least one child at home. The corresponding census figures are 48% with no children and 52% with at least one child. Test the null hypothesis that the
Vouchers for schools? A national opinion poll found that 42% of all American adults agree that parents should be given vouchers good for education at any public or private school of their choice. The result was based on a small sample. How large an SRS is required to obtain a margin of error of
More on demographics. In the previous exercise we arbitrarily chose to state the hypotheses in terms of the proportion of rural respondents. We could as easily have used the proportion of urban respondents.(a) Write hypotheses in terms of the proportion of urban residents to examine how well the
Checking the demographics of a sample. Of the 500 households that responded to the Christmas tree marketing survey, 38% were from rural areas (including small towns), and the other 62% were from urban areas (including suburbs).According to the census, 36% of Indiana households are in rural areas,
Can we use the z test? In each of the following cases, is the sample large enough to permit safe use of the z test? (The population is very large.)(a) n = 12 and H0: p = 0.6.(b) n = 100 and H0: p = 0.4.(c) n = 1000 and H0: p = 0.98.(d) n = 500 and H0: p = 0.3.
Financial goals of college students. In recent years over 70% of first-year college students responding to a national survey have identified “being well-off financially” as an important personal goal. A state university finds that 141 of an SRS of 200 of its first-year students say that this
Power companies and trimming trees. Large trees growing near power lines can cause power failures during storms when their branches fall on the lines. Power companies spend a great deal of time and money trimming and removing trees to prevent this problem. Researchers are developing hormone and
Shipping the orders on time. As part of a quality improvement program, your mail-order company is studying the process of filling customer orders. According to company standards, an order is shipped on time if it is sent within 2 working days of the time it is received. You select an SRS of 150 of
Christmas tree marketing. One question in the Christmas tree market survey described in Case 8.2 was “Did you have a Christmas tree last year?” Of the 500 respondents, 421 answered “Yes.”(a) What proportion of the sampled households responded“Yes”?(b) Give the standard error for your
Marketing pet care products to older adults. You have been asked to investigate the possibility of a marketing campaign to promote your company’s pet care products to older adults.Your report will include information about your potential market. In a study of the relationship between pet
High school students and diets. 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 diets. For a study of unhealthy eating behaviors, 267 college women aged 18 to 25 years were surveyed.14 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
How would the confidence interval change? Refer to Exercise 8.23.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.
How would the confidence interval change? Refer to Exercise 8.25.Would a 95% confidence interval be wider or narrower than the one that you found in that exercise? Verify your results by computing the interval.
How many credit cards? The survey described in the previous exercise reported that 43% of undergraduates had four or more credit cards. Give a 95% confidence interval for the proportion of all college students who have four or more credit cards.
Are the congregations conservative? The study described in the previous exercise also asked each respondent to classify his or her congregation according to theological orientation. For this question, 707 out of 1191 congregations were classified as “more conservative.” Using the questions in
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.12 One question concerned the length of the typical sermon. For 390 out of 1191 congregations, the typical sermon lasted
Dogs or rats to find cocaine (optional). Dogs are big and expensive. Rats are small and cheap. Can rats be trained to replace dogs in sniffing out illegal drugs? One study trained six male albino Sprague-Dawley rats to rear up on their hind legs in response to the smell of cocaine.11 After
Showing 300 - 400
of 8686
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Last
Step by Step Answers
Get 50% OFF
Study Help!
Claim Now
