Question: The manager of a dairy is in

> An inspector for the Atlantic City Gaming Commission suspects that a particular blackjack dealer may be cheating (in favor of the casino) when he deals at expensive tables. To test her belief, she observed 500 hands each at the $100- limit table and the

> Medical experts advocate the use of vitamin and mineral supplements to help fight infections. A study undertaken by researchers at Memorial University recruited 96 men and women age 65 and older. One-half of them received daily supplements of vitamins an

> Many small retailers advertise in their neighborhoods by sending out flyers. People deliver these to homes and are paid according to the number of flyers delivered. Each deliverer is given several streets whose homes become their responsibility. One of t

> Approximately 20 million Americans work for themselves. Most run single-person businesses out of their homes. One-quarter of these individuals use personal computers in their businesses. A market research firm, Computer Intelligence InfoCorp, wanted to k

> Most English professors complain that students don’t write very well. In particular they point out that students often confuse quality and quantity. A study at the University of Texas examined this claim. In the study undergraduate students were asked to

> There are currently 121,678 people waiting for lifesaving organ transplants in the United States. Of these, 100,791 await kidney transplants. (as of January 2016). The median wait time for an individual’s first kidney transplant is 3.6 years and can vary

> Personal spending is usually an indicator of the health of the overall economy. An increase tends to indicate that consumers are optimistic; a decrease indicates pessimism. Gallup tracks the spending of a random sample of American adults. The results for

> After observing the results of the test in Exercise 13.211, a statistics practitioner organized another experiment. People were matched according to gender, height, and weight. One member of each matched pair then exercised vigorously twice a week and th

> Most people exercise in order to lose weight. To determine better ways to lose weight, a random sample of male and female exercisers was divided into groups. The first group exercised vigorously twice a week. The second group exercised moderately four ti

> The Program for International Student Assessment (PISA) conducts tests of 15-year-olds. The tests jointly developed by the participating countries are tests for reading literary test, mathematical literacy test, and scientific literary test. Random sampl

> High blood pressure (hypertension) is a leading cause of strokes. Medical researchers are constantly seeking ways to treat patients suffering from this condition. A specialist in hypertension claims that regular aerobic exercise can reduce high blood pre

> Clinical depression is linked to several other diseases. Scientists at Johns Hopkins University undertook a study to determine whether heart disease is one of these. A group of 1190 male medical students was tracked over a 40-year period. Of these, 132 h

> Researchers at the University of Ohio surveyed 219 students and found that 148 had Facebook accounts. All students were asked how for their current GPA. Do the data allow us to infer that Facebook users have lower GPAs?

> The growing use of bicycles to commute to work has caused many cities to create exclusive bicycle lanes. These lanes are usually created by disallowing parking on streets that formerly allowed curbside parking. Merchants on such streets complain that the

> Refer to Exercise 13.205. Can we conclude that the defective rate differs between the two machines? Data from Exercise 13.205: Before deciding which of two types of stamping machines should be purchased, the plant manager of an automotive parts manufact

> Before deciding which of two types of stamping machines should be purchased, the plant manager of an automotive parts manufacturer wants to determine the number of units that each produces. The two machines differ in cost, reliability, and productivity.

> Have North Americans grown to distrust television and newspaper journalists? A study was conducted this year to compare what Americans currently think of the press versus what they said 3 years ago. The survey asked respondents whether they agreed that t

> In a study to determine whether gender affects salary offers for graduating MBA students, 25 pairs of students were selected. Each pair consisted of a female and a male student who were matched according to their GPAs, courses taken, ages, and previous w

> In designing advertising campaigns to sell magazines, it is important to know how much time each of a number of demographic groups spends reading magazines. In a preliminary study, 40 people were randomly selected. Each was asked how much time per week h

> An important component of the cost of living is the amount of money spent on housing. Housing costs include rent (for tenants), mortgage payments and property tax (for home owners), heating, electricity, and water. An economist undertook a 5-year study t

> As large cities grow larger, traffic congestion also increases. To measure how commuting time differs between California, New York, and Texas, random samples of commuters in each state were drawn. Is there sufficient evidence to infer that differences in

> Review the results of Exercises 15.1–15.3. What is the effect of decreasing the sample size?

> In recent years, a number of state governments have passed mandatory seat-belt laws. Although the use of seat belts is known to save lives and reduce serious injuries, compliance with seat-belt laws is not universal. In an effort to increase the use of s

> The city of Toronto boasts four daily newspapers. Not surprisingly, competition is keen. To help learn more about newspaper readers, an advertiser selected a random sample of people who bought their newspapers from a street vendor and people who had the

> Research scientists at a pharmaceutical company have recently developed a new nonprescription sleeping pill. They decide to test its effectiveness by measuring the time it takes for people to fall asleep after taking the pill. Preliminary analysis indica

> How important to your health are regular vacations? In a study a random sample of men and women were asked how frequently they take vacations. The men and women were divided into two groups each. The members of group 1 had suffered a heart attack; the me

> Every year, the Bureau of Labor Statistics administers a survey of American households called the American Time Use Survey. Respondents are asked to report their activities during an entire 24-hour day. The results are used to determine the number of hou

> A restaurant located in an office building decides to adopt a new strategy for attracting customers to the restaurant. Every week it advertises in the city newspaper. To assess how well the advertising is working, the restaurant owner recorded the weekly

> Obesity among children is quickly becoming an epidemic across North America. Television and video games are part of the problem. To gauge to what extent nonparticipation in organized sports contributes to the crisis surveys of children 5 to 14 years old

> Exercise 13.137 described the experiment that determined that taking aspirin daily reduces one’s probability of suffering a heart attack. The study was conducted in 1982 and at that time the mean age of the physicians was 50. In the years following the e

> In a study that was highly publicized, doctors discovered that aspirin seems to help prevent heart attacks. The research project, which was scheduled to last for 5 years, involved 22,000 American physicians (all male). Half took an aspirin tablet three t

> Plavix is a drug that is given to angioplasty patients to help prevent blood clots. A researcher at McMaster University organized a study that involved 12,562 patients in 482 hospitals in 28 countries. All the patients had acute coronary syndrome, which

> Refer to Exercise 12.131 where the statistics practitioner estimated the size of market segments based on education among California adults. Suppose that census figures from 10 years ago showed the education levels and the proportions of California adult

> Cold and allergy medicines have been available for a number of years. One serious side effect of these medications is that they cause drowsiness, which makes them dangerous for industrial workers. In recent years, a nondrowsy cold and allergy medicine ha

> The process that is used to produce a complex component used in medical instruments typically results in defective rates in the 40% range. Recently, two innovative processes have been developed to replace the existing process. Process 1 appears to be mor

> Surveys have been widely used by politicians around the world as a way of monitoring the opinions of the electorate. Six months ago, a survey was undertaken to determine the degree of support for a national party leader. Of a sample of 1,100, 56% indicat

> One hundred normal-weight people and 100 obese people were observed at several Chinese-food buffets. For each researcher recorded whether the diner used chopsticks or knife and fork. The table shown here was created. Is there sufficient evidence at the

> A firm has classified its customers in two ways: (1) according to whether the account is overdue and (2) whether the account is new (less than 12 months) or old. To acquire information about which customers are paying on time and which are overdue, a ran

> Many stores sell extended warranties for products they sell. These are very lucrative for store owners. To learn more about who buys these warranties a random sample of a store’s customers who recently purchased a product for which an e

> After sampling from two binomial populations we found the following. a. Estimate with 90% confidence the difference in population proportions. b. Repeat part (a) increasing the sample proportions to .48 and .52, respectively. c. Describe the effects of i

> These statistics were calculated from two random samples: a. Calculate the p-value of a test to determine whether there is evidence to infer that the population proportions differ. b. Repeat part (a) with p^1 = .95 and p^2 = .90. c. Describe the effect o

> Random samples from two binomial populations yielded the following statistics: a. Calculate the p-value of a test to determine whether we can infer that the population proportions differ. b. Repeat part (a) increasing the sample sizes to 400. c. Describe

> An important statistical measurement in service facilities (such as restaurants and banks) is the variability in service times. As an experiment, two bank tellers were observed, and the service times for each of 100 customers were recorded. Do these data

> Using the data supplied by NOAA National Weather Service, 19,450 tornadoes struck the United States between 2000 and 2014. The percentage for each month is listed here. The monthly number of tornadoes for 2015 was recorded. Is there enough statistical e

> In deciding where to invest her retirement fund, an investor recorded the weekly returns of two portfolios for 1 year. Can we conclude that portfolio 2 is riskier than portfolio 1?

> In Exercise 12.80 we described the problem of whether to change all the light bulbs at Yankee Stadium or change them one by one as they burn out. There are two brands of bulbs that can be used. Because both the mean and the variance of the lengths of lif

> A new highway has just been completed and the government must decide on speed limits. There are several possible choices. However, on advice from police who monitor traffic the objective was to reduce the variation in speeds, which it is thought to contr

> A statistics professor hypothesized that not only would the means vary, but also so would the variances if the business statistics course was taught in two different ways but had the same final exam. He organized an experiment wherein one section of the

> An operations manager who supervises an assembly line has been experiencing problems with the sequencing of jobs. The problem is that bottlenecks are occurring because of the inconsistency of sequential operations. He decides to conduct an experiment whe

> Random samples from two normal populations produced the following statistics: a. Estimate with 95% confidence the ratio of the two population variances. b. Repeat part (a) changing the sample sizes to n1 = 25 and n2 = 25. c. Describe what happens to the

> Random samples from two normal populations produced the following statistics: a. Can we infer at the 10% significance level that the two population variances differ? b. Repeat part (a) changing the sample sizes to n1 = 15 and n2 = 15. c. Describe what ha

> Refer to Example 13.2. The actual after and before operating incomes were recorded. a. Test to determine whether there is enough evidence to infer that for companies where an offspring takes the helm there is a decrease in operating income. b. Is there s

> Discuss why the experiment in Example 13.5 produced a significant test result whereas the one in Exercise 13.103 did not.

> From January 1 to December 31, 2011, there were 5,086 bank robberies in the United States. The percentage of that total for each day of the week is listed next. The number of robberies per day for the first two months of 2016 was recorded. Can we infer t

> Refer to Examples 13.4 and 13.5. Suppose that another experiment is conducted. Finance and marketing MBA majors were matched according to their undergraduate GPA. As in the previous examples, the highest starting salary offers were recorded. Can we infer

> Refer to Exercises 13.33 and 13.101. Explain why the matched pairs experiment produced significant results whereas the independent samples t-test did not. Data from Exercise 13.33: Tire manufacturers are constantly researching ways to produce tires that

> Refer to Exercise 13.33. Suppose now we redo the experiment in the following way. On 20 randomly selected cars, one of each type of tire is installed on the rear wheels and as before, the cars are driven until the tires wear out. The number of miles unti

> Every April Americans and Canadians fill out their tax return forms. Many turn to tax preparation companies to do this tedious job. The question arises, Are there differences between companies? In an experiment two of the largest companies were asked to

> Telemarketers obtain names and telephone numbers from several sources. To determine whether one particular source is better than a second, a random sample of names and numbers from the two different sources was obtained. For each potential customer, a st

> Quik Lube is a company that offers oil change service while the customer waits. Its market has been broken down into the following segments: 1. Working men and women too busy to wait at a dealer or service center 2. Spouses who work in the home 3. Retire

> The market for breakfast cereals has been divided into several segments related to health. One company identified a segment as those adults who are health conscious. The marketing manager would like to know whether this segment is more likely to purchase

> A Gallup survey asks a random sample of American adults this question. “In this country, are you satisfied or dissatisfied with your freedom to choose what you do with your life?” The responses are 1 = satisfied, 2 = dissatisfied. The survey results from

> Surveys of workers asked a series of questions from which each was categorized as either 1 = thriving, 2 = struggling, 3 = suffering. Each respondent was also asked whether they worked for the federal government or a private sector employer. Is there suf

> In June 2016 the United Kingdom voted to leave the European Union. As is the case in the United States, pollsters conducted exit polls and asked how each respondent voted (1 = remain, 2 = leave) and recorded the age category (1 = 18 – 24, 2 = 25 – 49, 3

> An aging pitcher has recorded the following pitch distribution over his long career from 1995 to 2014. 1. Fast ball 52% 2. Curve ball 19% 3. Slider 15% 4. Changeup 14% However, undergoing a surgery to repair a tendo

> Refer to Exercise 13.159. The fan also recorded the calls on pitches that were in the strike zone and the batter did not swing (1 = ball, 2 = strike). Can we infer from the data that there is a difference in the error rate of making calls on pitches in t

> In Exercise 9.59 we pointed out that most televised baseball games display a pitch tracker that shows whether the pitch was a ball or a strike, which in turn shows whether the umpire made the correct call. Suppose a fan kept track of a random sample of c

> To measure the cardiovascular health of Canadians, cardiologists developed the Cardiovascular Health in Ambulatory Care Research Team (CANHEART) health index. A score of 1 is assigned for each of the following cardiovascular health factors and behaviors:

> Refer to Exercise 13.156. In 2700 of the resumes the religion mentioned was one of the mainstream religions. However, 500 resumes made reference to a made-up religion – Wallonian. The religious designation (1 = mainstream religion, 2 = Wallonian) was rec

> An experiment conducted by members of the Religious Affiliation and Hiring Discrimination Organization to determine what shouldn’t be in the resume should be of interest to students preparing resumes in search of summer or permanent jobs. The experiment

> One of the issues in the U.S. presidential election in 2016 was the Keystone XL pipeline, which would send Canadian oil to the refineries in Texas. Pew Research Center conducted a survey of American adults and asked each whether he or she was in favor (

> In Chapters 3 and 4, we described the issue of global warming pointing out that the Earth has not warmed since 1998, explaining why the media now refer to the problem as climate change, and that there is a weak linear relationship between temperature ano

> Are Americans becoming more unhappy at work? A survey of Americans in 2008 and again this year asked whether he or she was satisfied with their jobs (1 = No, 2 = Yes). Can we infer that more Americans are unhappy compared to 2008?

> Parents often urge their children to get more education, not only for the increased income but to perhaps work less hard. In a survey, a random sample of Canadians were asked whether they work 11 or more hours a day (1 = No, 2 = Yes) and whether they com

> An operations manager of a computer chip maker is in the process of selecting a new machine to replace several older ones. Although technological innovations have improved the production process, it is quite common for the machines to produce defective c

> Refer to Exercise 15.15. After an entire season of pitches, the following proportions for all pitches were observed. A rookie pitcher starts his first game and the pitch outcome was recorded using the codes. Is there enough evidence at the 5% significan

> It has been estimated that the oil sands in Alberta Canada contains 2 trillion barrels of oil. However, recovering the oil damages the environment. A survey of Canadians and Americans asked, What is more important to you with regard to the oilsands, envi

> Has the illicit use of drugs decreased over the past 10 years? Government agencies have undertaken surveys of Americans 12 years of age and older. Each was asked whether he or she used drugs at least once in the previous month. The results of this year’s

> An insurance company is thinking about offering discounts on its life insurance policies to nonsmokers. As part of its analysis, the company randomly selects 200 men who are 60 years old and asks them whether they smoke at least one pack of cigarettes pe

> Automobile magazines often compare models and rate them in various ways. One question that is often asked of car owners, Would you buy the same model again? Suppose that a researcher for one magazine asked a random sample of Lexus owners and a random sam

> The objective in Exercise 13.165 was to determine whether various market segments were more likely to use the QuikLube service. Included with the data is also the age (in months) of the car. Do the data allow us to conclude that there are differences in

> Exercise 13.21 addressed the problem of determining whether the distances young (under 25) males and females drive annually differ. Included in the data is also the number of accidents that each person was involved in the past 2 years. Responses are 0, 1

> In Exercise 12.132 marketing managers for the JC Penney department store chain segmented the market for women’s apparel on the basis of personal and family values. The segments are Conservative, Traditional, and Contemporary. Recall that the classificati

> A random sample of 175 people who had lunch at a company cafeteria were offered a brownie. Some were handed the brownie on a fine piece of china, others were given the brownie on a paper plate, and others were given the brownie on a paper napkin. Each pe

> Deskbound secretaries were employed in this experiment. Clear-lidded candy dished filled with 30 Hershey’s Kisses were placed in three different locations. The first location was the secretary’s desk, the second was the top-left drawer in the secretary’

> This experiment consisted of graduates students given either a medium-sized 17-ounce bowls or large-sized 34-ounce bowls. Each student was invited to take as much of four different flavors of ice cream as he or she wanted. The size of the scoop also vari

> Pitch trackers allow baseball fans watching televised games to see whether an umpire made the correct call. After tracking all pitches over an entire season, the following probabilities were recorded. A new umpire has just started and the pitch tracker

> A study described in the British Medical Journal (January 2004) sought to determine whether exercise would help extend the lives of patients with heart failure. A sample of 801 patients with heart failure was recruited; 395 received exercise training and

> The National Center for Charitable Statistics estimates that individual giving in the United States in 2014 was $258.51 billion. A study to determine who gave and how much they gave was undertaken. A random sample of individuals who gave to charities was

> Automobile insurance companies use statistics to determine their premiums. The premiums are proportional to the risks and costs of accidents. Suppose that an economist conducted a study that looked at miles driven in the previous year, ages of the driver

> St Catharine’s-Niagara, Kitchener- Cambridge-Waterloo. Brantford, Guelph, London, and Windsor are relatively small cities in Southwest Ontario. Because of their size the expectation is that the time it takes to get from home to work would not be large. T

> Refer to Exercise 14.135. Do Americans spend more on health care as they age? To answer the question, economists turned to the Bureau of Labor Statistics to measure how much Americans in the following age groups spend annually on health care. (1) 55–64

> The U.S. Bureau of Labor Statistics conducts regular surveys to determine how Americans are spending their money. The annual expenditures for vehicle insurance of a random sample of American households in 2012, 2013, and 2014 were recorded. Is there suff

> Each year Michigan State University’s Collegiate Employment Research Institute tracks starting salaries of graduates. The Institute recorded the starting salaries of the following engineers: chemical, civil, computer, electrical, and mechanical. a. Is th

> Another useful measure of Americans’ beliefs about the state of the economy is the age at which they believe they will retire. If nonretired people believe that they will need to work longer to be able to afford their lifestyle after retirement it likely

> Does the day a house is listed for sale affect how long it takes for the sale to be completed or its selling price? A study conducted by economists attempted to answer the question. A random sample of houses that sold in a major city was studied. The num

> Refer to Exercise 14.129. A similar study determined the monthly household income of households headed by 25- to 34-year-olds with only a high school diploma. The incomes were converted to 2012 dollars. a. Is there sufficient evidence to infer that house

> In an election held last year that was contested by three parties. Party A captured 31% of the vote, party B garnered 51%, and party C received the remaining votes. A survey of 1,200 voters asked each to identify the party that they would vote for in the

> Refer to Exercise 14.129. A similar study was conducted for Bachelor’s degrees. a. Can we infer from the data that incomes differed for 25- to 34-year-olds with Bachelor’s degrees between the three periods? b. Are the required conditions satisfied? Expla

> How have 25- to 34-year-olds with university degrees fared financially since 1984? To answer this question, the Pew Research Center conducted surveys in 1984, 1996, and 2009 recording monthly earnings for graduates with three different types of degrees.