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business statistics a first course
Introduction To Business Statistics 7th Edition Ronald M. Weiers - Solutions
12.22 A one-way ANOVA has been conducted for an experiment in which there are three treatments and each treatment group consists of 10 persons. The results include the sum of squares terms shown here. Based on this information, construct the ANOVA table of summary findings and use the 0.025 level
12.21 In a one-way ANOVA, there are two independent samples, with n1 5 20 and n2 5 15. The calculated F-statistic is F 5 3.60. At the 0.05 level of significance, what conclusion would be reached? Based on the F distribution tables, what is the most accurate statement that can be made about the
12.20 In a one-way ANOVA, there are three independent samples, with n1 5 8, n2 5 10, and n3 5 7. The calculated F-statistic is F 5 3.95. At the 0.05 level of significance, what conclusion would be reached? Based on the F distribution tables, what is the most accurate statement that can be made
12.19 In using ANOVA to compare the means of several samples, what value would be expected for the calculated F-statistic if the population means really are the same?Explain.
12.18 On snow-covered roads, winter tires enable a car to stop in a shorter distance than if summer tires were installed. In terms of the additive model for one-way ANOVA, and for an experiment in which the mean stopping distances on a snow-covered road are measured for each of five brands of
12.17 In terms of the assumptions required for using ANOVA, what is the special relevance of the value calculated for the error mean square, MSE?
12.16 For the one-way ANOVA model, xij 5 1 j 1 ij, explain the meaning of each term in the equation, then use the appropriate terms from the equation in presenting and explaining the null and alternative hypotheses to be examined.
Why is the F distribution applicable to ANOVA?
What assumptions are required in using the one-way ANOVA?
What is the purpose of the one-way ANOVA?
12.12 The accompanying dotplots represent independent samples. Would you tend to reject the null hypothesis that A 5 B? Explain. + 20 : :. : 40 60 80 100 120 -SAMPLEA -SAMPLEB
For the experiment described in Exercise 12.8, identify the dependent and independent variables. Indicate whether each variable is quantitative or qualitative.
For the experiment described in Exercise 12.7, identify the dependent and independent variables. Indicate whether each variable is quantitative or qualitative.
For the experiment described in Exercise 12.6, identify the dependent and independent variables. Indicate whether each variable is quantitative or qualitative.
From each of four suppliers, a quality-control technician collects a random sample of 10 rivets, then measures the number of pounds each will withstand before it fails. Does this represent a designed experiment?Explain.
Twenty accounting students are randomly assigned to two different sections of an intermediate accounting class. Each section ends up consisting of 10 students. In one of the sections, computer-assisted instruction and review software is utilized; in the other section, it is not.All students are
A university president collects data showing the number of absences over the past academic year for a random sample of 6 professors in the College of Engineering. She does the same for a random sample of 9 professors in the College of Business and for a random sample of 8 professors in the College
Differentiate between the independent and dependent variables in an experiment.
Explain the basic role that between-sample variation and within-sample variation play in carrying out an analysis of variance.
What is necessary for an experiment to be“balanced”?
“A factor level is the same as a treatment.” Is this statement always true? If not, what conditions are necessary for it to be true?
What is meant by a designed experiment?
11.101 An anthropologist studying personal advertisements in a Utica, New York, newspaper has observed whether the advertiser included a mention of an interest in the outdoors in his or her ads. According to the anthropologist, citing the outdoors “may be taken to imply not only good life habits,
11.100 The data in file XR11100 are the weights (in grams) for random samples of grain packages filled by two different filling machines. The machines have a fine adjustment for the mean amount of fill, but the standard deviations are inherent in the design of the grain delivery mechanism. Based on
11.99 A company that makes an athletic shoe designed for basketball has stated in its advertisements that the shoe increases the jumping ability of players who wear it.The general manager of a professional team has conducted a test in which each player’s vertical leap is measured with the current
11.98 A supermarket manager is examining whether a new plastic bagging configuration in the produce area might make it more efficient for customers who are bagging their own fruits and vegetables. She observes a sample of customers using the new system and a sample of customers using the standard
11.97 Three years after receiving their degrees, graduates of a university’s MBA program have reported their annual salary rates, with a portion of the data listed in file XR11097. Graduates in one of the groups represented in the data are employed by consulting firms, while another group
11.96 Given the information in Exercise 11.76, and using the 0.01 level of significance in comparing the sample standard deviations, were we justified in assuming that the population standard deviations were equal? Would your conclusion change if the standard deviation of the data values with the
11.95 Given the information in Exercise 11.75, and using the 0.05 level of significance in comparing the sample standard deviations, were we justified in assuming that the population standard deviations were equal?Would your conclusion change if the standard deviation of the estimates received by
11.94 A study by Experian found that 20% of consumers in New Jersey have 10 or more credit cards, compared to 11% in Tennessee. In a two-tail test at the 0.05 level of significance, and assuming the percentages are from independent samples of 100 consumers each, can we conclude that New Jersey and
11.93 According to the National Center for Education Statistics, 88% of elementary, middle-school, and secondaryschool students from families earning $75,000 or more per year use a computer at school, compared to 81% from families earning less than $20,000. Using a one-tail test at the 0.01 level,
11.92 A maintenance engineer has been approached by a supplier who promises less downtime for machines using its new molybdenum-based super lubricant. Of 120 machines maintained with the new lubricant, only 20%were out of service for more than an hour during the month of the test, while 30% of the
11.91 In tests of a speed-reading course, it is found that 10 subjects increased their reading speed by an average of 200 words per minute, with a standard deviation of 75 words. At the 0.10 level, does this sample information suggest that the course is really effective in improving reading speed?
11.90 A pharmaceutical manufacturer has come up with a new drug intended to provide greater headache relief than the old formula. Of 250 patients treated with the previous medication, 130 reported “fast relief from headache pain.” Of 200 individuals treated with the new formula, 128 said they
11.89 An Internal Revenue Service manager is comparing the results of recent taxpayer interviews conducted by two auditors. Of 200 taxpayers audited by Ms. Smith, 30% had to pay additional taxes. Of 100 audited by Mr.Burke, only 19% paid additional taxes. At the 0.01 level of significance, can the
11.88 A motel manager, concerned with customer theft of towels, decided that the theft rate might be reduced by changing from white, imprinted towels to a drab green version. Of the 120 guests provided with the white towels, 35% took at least one towel with them when they checked out. Of the 160
11.87 The idling speed of 14 gasoline-powered generators is measured with and without an oil additive that is designed to lower friction. With the additive installed, the mean change in speed was 123 revolutions per minute (rpm), with a standard deviation of 3.5 rpm. At the 0.05 level of
11.86 In an experiment comparing a new long- distance golf ball with the conventional design, each of 20 golfers hits one drive with each ball. The average golfer in the sample hit the new ball 9.3 yards farther, with a standard deviation of 10.5 yards. At the 0.005 level, evaluate the
11.85 Observing a sample of 35 morning customers at a convenience store, a researcher finds their average stay in the store is 3.0 minutes, with a standard deviation of 0.9 minutes. For a sample of 43 afternoon customers, the mean and standard deviation were 3.5 and 1.8 minutes, respectively. Using
11.84 Two machines are supposed to be producing steel bars of approximately the same length. A sample of 35 bars from one machine has an average length of 37.013 inches, with a standard deviation of 0.095 inches. For 38 bars produced by the other machine, the corresponding figures are 36.974 inches
11.83 For a sample of 48 finance majors, the average time spent reading each issue of the campus newspaper is 19.7 minutes, with a standard deviation of 7.3 minutes.The corresponding figures for a sample of 40 management information systems majors are 16.3 and 4.1 minutes.Using the 0.01 level of
11.82 A sample of 25 production employees has been tested twice on a standard test of manual dexterity. The average change in the time required to finish the test was a decrease of 1.5 minutes, with a standard deviation of 0.3 minutes. At the 0.05 level, can we conclude that the average production
11.81 Independent random samples of vehicles traveling past a given point on an interstate highway have been observed on Monday versus Wednesday. For 16 cars observed on Monday, the average speed was 59.4 mph, with a standard deviation of 3.7 mph. For 20 cars observed on Wednesday, the average
11.80 The developer of a new welding rod claims that spot welds using his product will have greater strength than conventional welds. For 45 welds using the new rod, the average tensile strength is 23,500 pounds per square inch, with a standard deviation of 600 pounds.For 40 conventional welds on
11.79 Bob Techster is very serious about winning this year’s All-American Soap Box Derby competition. Since there is no wind-tunnel time available at the aerospace firm where his father works, Bob is using a local hill to test the effectiveness of an aerodynamic design change.In 10 runs with the
11.78 An industrial engineer has designed a new workstation layout that she claims will increase production efficiency. For a sample of 8 workers using the new workstation layout, the average number of units produced per hour is 36.4, with a standard deviation of 4.9.For a sample of 6 workers using
11.77 A compressor manufacturer is testing two different designs for an air tank. Testing involves pumping air into a tank until it bursts, then noting the air pressure just prior to tank failure. Four tanks of design A are found to fail at an average of 1400 pounds per square inch (psi), with a
11.76 The manufacturer of a small utility trailer is interested in comparing the amount of fuel used in towing the trailer with that required to overcome the weight and wind resistance of a rooftop carrier. Over a standard test route at highway speeds, 8 trips with the trailer resulted in an
11.75 Suspecting that television repair shops tend to charge women more than they do men, Emily disconnected the speaker wire on her portable television and took it to a sample of 12 shops. She was given repair estimates that averaged $85, with a standard deviation of$28. Her friend John, taking
11.74 An investment analyst has data for the past 8 years on each of two mutual funds, with the annual rates of return for each listed in file XR11074. On average, each fund has had an excellent annual rate of return over the time period for his data, but the analyst is concerned that a mutual fund
11.73 For independent samples of customers of Internet providers A and B, the ages are as listed in file XR11073.Using the 0.05 level of significance in a nondirectional test, examine whether the variation in ages could be the same for customers of the two providers.
11.72 A researcher has observed independent samples of females and males, recording how long each person took to complete his or her shopping at a local mall. The respective times, in minutes, are listed in file XR11072. Using the 0.025 level of significance in a onetail test, would females appear
11.71 In conducting her annual review of suppliers, a purchasing agent has collected data on a sample of orders from two of her company’s leading vendors. On average, the 24 shipments from company 1 have arrived 3.4 days after the order was placed, with a standard deviation of 0.4 days. The 30
11.70 According to the National Association of Homebuilders, the average life expectancies of a dishwasher and a microwave oven are about the same:9 years. Assume that their finding was based on a sample of n1 5 60 dishwashers and n2 5 40 microwave ovens, and that the corresponding sample standard
11.69 Given the information in Exercise 11.11, and using the 0.05 level of significance in comparing the sample standard deviations, were we justified in assuming that the population standard deviations were equal?Would your conclusion change if the standard deviation for the FoodFarm jars had been
11.68 Given the information in Exercise 11.10, and using the 0.02 level of significance in comparing the sample standard deviations, were we justified in assuming that the population standard deviations are equal? Would your conclusion change if the standard deviation of playing times for music
11.67 For two samples from what are assumed to be normally distributed populations, the sample sizes and standard deviations are n1 5 28, s1 5 103.1, n2 5 41, and s2 5 133.5. At the 0.10 level of significance, test the null hypothesis that the population variances are equal. Would your conclusion
11.66 For two samples from what are assumed to be normally distributed populations, the sample sizes and standard deviations are n1 5 10, s1 5 23.5, n2 5 9, and s2 5 10.4. At the 0.10 level of significance, test the null hypothesis that the population variances are equal. Would your conclusion be
11.65 A study by the National Marine Manufac turers Association found that 12.2% of those who participated in sailing were females age 25–34. Of those who participated in horse back riding during the same period, 14.7%were females in this age group. Assume that file XR11065 contains the
11.64 Attempting to improve the quality of services provided to customers, the owner of a chain of high-fashion department stores randomly selected a number of clerks for special training in customer relations. Of this group, only 10% were the subject of complaints to the store manager during the 3
11.63 An American Express survey of small-business owners found that 71% of female owners feel stressed by their work/life balance, compared to 62% of their male counterparts. Assume that file XR11063 contains the underlying sample data for female and male smallbusiness owners, respectively, with
11.62 According to the ICR Research Group, 63% of Americans in the 18–34 age group say they are comfortable filing income tax returns electronically, compared to just 49% of those who are 55–64. Using the 0.025 level of significance, and assuming there were 200 persons surveyed from each age
11.61 In a preliminary study, the U.S. Veterans Affairs Department found that 30.9% of the 81 soldiers who were near an accidental nerve gas release just after the 1991 Persian Gulf War had muscle and bone ailments, compared to a rate of 23.5% for the 52,000 Gulf veterans who were not near that
11.60 A telephone sales solicitor, trying to decide between two alternative sales pitches, randomly alternated between them during a day of calls. Using approach A, 20% of 100 calls led to requests for the mailing of additional product information. For approach B in another 100 calls, only 14% led
11.59 Community National Bank is using an observational study to examine the utilization of its new 24-hour banking machine. Of 300 males who used the machine last week, 42% made two or more transactions before leaving.Of 250 female users during the same period, 50% made at least two transactions
11.58 Of 200 subjects approached by interviewer A, 45 refused to be interviewed. Of 120 approached by interviewer B, 42 refused an interview. At the 0.05 level of significance, can we reject the possibility that the interviewers are equally capable of obtaining interviews?
11.57 During the course of a year, 38.0% of the 213 merchant ships lost were general cargo carriers, while 43.8% of the 219 ships lost during the following year were in this category. Using a two-tail test at the 0.05 level, examine whether this difference could have been the result of chance
11.56 In a study by the United Dairy Industry Association, 42% of 655 persons age 35–44 said they seldom or never ate cottage cheese. For 455 individuals age 45–54, the corresponding percentage was 34%. At the 0.01 level, can we reject the possibility that the population percentages could be
11.55 In examining the ability of users to complete a variety of information-seeking tasks on their mobile devices, Nielsen Norman Group assigned sample members to get the answers to a variety of questions like,“How many calories are there typically in a slice of thincrust pizza?” The success
11.54 A bank manager has been presented with a new brochure that was designed to be more effective in attracting current customers to a personal financial counseling session that would include an analysis of additional banking services that could be advantageous to both the bank and the customer.
11.53 Summary data for two independent samples are p1 5 0.31, n1 5 400, and p2 5 0.38, n2 5 500. Use the 0.05 level of significance in testing H0: 1 5 2 versus H1: 1 Þ 2.
11.52 Summary data for two independent samples are p1 5 0.36, n1 5 150, and p2 5 0.29, n2 5 100. Use the 0.025 level of significance in testing H0: 1 # 2 versus H1: 1 . 2.
11.51 A plant manager has collected productivity data for a sample of workers, intending to see whether there is a difference in the number of units they produce on Monday versus Thursday. The results (units produced)are in data file XR11051. Using the 0.01 level of significance, evaluate the null
11.50 For a special pre–New Year’s Eve show, a radio station personality has invited a small panel of prominent local citizens to help demonstrate to listeners the adverse effect of alcohol on reaction time. The reaction times (in seconds) before and after consuming four drinks are in data file
11.49 The students in an aerobics class have been weighed both before and after the 5-week class, with the following results:Using the 0.05 level of significance, evaluate the effectiveness of the program. Using the appropriate statistical table, what is the most accurate statement we can make
11.48 In an attempt to measure the emotional effect of a proposed billboard ad, an advertising agency checks the pulse rate of 10 persons before and after they are shown a photograph of the billboard. The agency believes that an effective billboard will increase the pulse rate of those who view it.
11.47 A trucking firm is considering the installation of a new, low-restriction engine air filter for its long-haul trucks, but doesn’t want to make the switch unless the new filter can be shown to improve the fuel economy of these vehicles. A test is set up in which each of 10 trucks makes the
11.46 A university president randomly selects 10 tenured faculty from the College of Arts and Sciences and 10 tenured faculty from the College of Business. Each faculty member is then asked to rate his or her job satisfaction on a scale of 1 (very dissatisfied) to 10 (very satisfied).Would this be
11.45 Each of 20 consumers is provided with a package containing two different brands of instant coffee.A week later, they are asked to rate the taste of each coffee on a scale of 1 (poor taste) to 10 (excellent taste). Is this an example of independent samples or dependent samples?
11.44 A pharmaceutical firm has checked the cholesterol levels for each of 30 male patients, then provided them with fish-oil capsules to take on a daily basis. The cholesterol levels are rechecked after a 1-month period. Does this study involve independent samples or dependent samples?
11.43 A study has been conducted to examine the effectiveness of a new experimental program for preparing high school students for the Scholastic Aptitude Test.Eighty students have been randomly divided into two groups of 40. The eventual SAT scores for those exposed to the new program and the
11.42 In planning the processes to be incorporated into a new manufacturing facility, engineers have proposed two possible assembly procedures for one of the phases in the production sequence. Sixty of the eventual production line workers have taken part in preliminary tests, with data representing
11.41 In their 2003 and 2008 studies on how long wireless customers have to spend on hold before speaking with a customer service representative, J.D. Power and Associates found the mean times to be 3.3 minutes and 4.4 minutes, respectively. Assume that data file XR11041 contains the data, in
11.40 According to a psychologist at the Medical College of Virginia, soccer players who “head” the ball 10 or more times a game are at risk for brain damage that could lower their intellectual abilities. In tests involving young male soccer players, those who typically headed the ball 10 or
11.39 A study found that women of normal weight missed an average of 3.4 days of work due to illness during the preceding year, compared to an average of 5.2 days for women who were considered overweight. Assuming (1) a sample size of 30 for each group and (2) sample standard deviations of 2.5 and
11.38 A study of 102 patients who had digestive-tract surgery found that those who chewed a stick of gum for 15 minutes at mealtimes ended up being discharged after an average of 4.4 days in the hospital, compared to an average of 5.2 days for their counterparts who were not provided with gum.
11.37 Surveys of dog owners in two adjacent towns found the average veterinary-related expense total for dog owners in town A during the preceding year was$240, with a standard deviation of $55, while the comparable results in nearby town B were $225 and $32, respectively. Assuming a sample size of
11.36 According to the U.S. Bureau of Labor Statistics, personal expenditures for entertainment fees and admissions averaged $349 per person in the Northeast and$420 in the West. Assuming that these data involved(1) sample sizes of 800 and 600 and (2) standard deviations of $215 and $325,
Repeat Exercise 11.21 using the z-test approximation to the unequal-variances t-test.
Repeat Exercise 11.20 using the z-test approximation to the unequal-variances t-test.
For the following independent random samples, use the z-test and the 0.05 level of significance in testing H0: 1 # 2 versus H1: 1 . 2.}x 1 5 85.2 s1 5 9.6 n1 5 40}x 2 5 81.7 s2 5 4.1 n2 5 32
For the following independent random samples, use the z-test and the 0.01 level of significance in testing H0: 1 5 2 versus H1: 1 ? 2.}x 1 5 33.5 s1 5 6.4 n1 5 31}x 2 5 27.6 s2 5 2.7 n2 5 30
Under what conditions is it appropriate to use the z-test as an approximation to the unequal-variances t-test when comparing two sample means?
11.30 During May 2009, visitors to usatoday.com spent an average of 12.2 minutes per visit, compared to 11.0 minutes for visitors to washingtonpost.com. Assuming that file XR11030 contains the sample data underlying these results, use the 0.01 level of significance in examining whether the
11.29 It has been reported that the average visitor from Japan spent $3120 during a trip to the United States, while the average for a visitor from the United Kingdom was$2654. Assuming that file XR11029 contains the survey data underlying these results, use the 0.05 level in examining whether the
11.28 When companies are designing a new product, one of the steps typically taken is to see how potential buyers react to a picture or prototype of the proposed product. The product-development team for a notebook computer company has shown picture A to a large sample of potential buyers and
11.27 According to a Yankelovich poll, women spend an average of 19.1 hours shopping during the month of December, compared to 12.7 hours for men. Assuming that file XR11027 contains the survey data underlying these results, use the 0.01 level in examining whether the sample mean for women is
11.26 One of the measures of the effectiveness of a stimulus is how much the viewer’s pulse rate increases on exposure to it. In testing a lively new music theme for its television commercials, an advertising agency shows ads with the new music to a sample of 25 viewers. Their mean pulse rate
11.25 According to a national Gallup poll, men visit the doctor’s office an average of 3.8 times per year, while women visit an average of 5.8 times per year. In a similar poll conducted in a Midwest county, a sample of 50 men visited the doctor an average of 2.2 times in the past year, with a
11.24 Safety engineers at a manufacturing plant are evaluating two brands of 50-ampere electrical fuses for possible purchase and use in the plant. One of the performance characteristics they are considering is how long the fuse will carry 50 amperes before it blows. In a sample of 35 fuses from
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