Is there a significant difference in the gasoline mileage of a car for regular unleaded and premium unleaded? To test this question, a business analyst randomly selected 15 drivers for a study. They were to drive their cars for one month on regular unleaded and for one month on premium unleaded gasoline. The participants drove their own cars for this experiment. The average sample difference was 2.85 miles per gallon in favor of the premium unleaded, and the sample standard deviation of difference was 1.9 miles per gallon. For α = .01, does the test show enough evidence for the business analyst to conclude that there is a significant difference in mileage between regular unleaded and premium unleaded gasoline? Assume the differences in gasoline mileage figures are normally distributed in the population.
> One of the thrusts of quality-control management is to examine the process by which a product is produced. This approach also applies to paperwork. In industries where large long-term projects are undertaken, days and even weeks may elapse as a change or
> A company’s auditor believes the per diem cost in Nashville, Tennessee, rose significantly between 2008 and 2019. To test this belief, the auditor samples 51 business trips from the company’s records for 2008; the sample average was $212 per day, with a
> Various types of retail outlets sell toys during the holiday season. Among them are specialty toy stores, large discount toy stores, and other retailers that carry toys as only one part of their stock of goods. Is there any difference in the dollar amoun
> Executives often spend so many hours in meetings that they have relatively little time to manage their individual areas of operation. What is the difference in mean time spent in meetings by executives of the aerospace industry and executives of the auto
> Is there a difference in the proportion of construction workers who are under 35 years of age and the proportion of telephone repair people who are under 35 years of age? Suppose a study is conducted in Calgary, Alberta, using random samples of 338 const
> A manufacturer uses two machines to drill holes in pieces of sheet metal used in engine construction. The workers who attach the sheet metal to the engine become inspectors in that they reject sheets so poorly drilled that they cannot be attached. The pr
> In manufacturing, does worker productivity drop on Friday? In an effort to determine whether it does, a company’s personnel analyst randomly selects from a manufacturing plant five workers who make the same part. He measures their outpu
> As the prices of heating oil and natural gas increase, consumers become more careful about heating their homes. Analysts want to know how warm homeowners keep their houses in January and how the results from Wisconsin and Tennessee compare. The analysts
> What is the average difference between the price of name-brand soup and the price of store-brand soup? To obtain an estimate, an analyst randomly samples eight stores. Each store sells its own brand and a national name brand. The prices of a can of name-
> Is there more variation in the output of one shift in a manufacturing plant than in another shift? In an effort to study this question, plant managers gathered productivity reports from the 8 A.M. to 4 P.M. shift for eight days. The reports indicated tha
> Cycle time in manufacturing can be viewed as the total time it takes to complete a product from the beginning of the production process. The concept of cycle time varies according to the industry and product or service being offered. Suppose a boat manuf
> A candy company fills a 20-ounce package of Halloween candy with individually wrapped pieces of candy. The number of pieces of candy per package varies because the package is sold by weight. The company wants to estimate the number of pieces per package.
> One of the most important aspects of a store’s image is the perceived quality of its merchandise. Other factors include merchandise pricing, assortment of products, convenience of location, and service. Suppose image perceptions of shoppers of specialty
> A tree nursery has been experimenting with fertilizer to increase the growth of seedlings. A sample of 35 two-year-old pine trees is grown for three more years with a cake of fertilizer buried in the soil near the trees’ roots. A second
> The Bureau of Labor Statistics shows that the average insurance cost to a company per hour worked for an employee by major industry group is $3.22 for construction workers and $3.97 for manufacturing workers. Suppose these figures were obtained from 14 c
> A national grocery store chain wants to test the difference in the average weight of turkeys sold in Detroit and the average weight of turkeys sold in Charlotte. According to the chain’s analyst, a random sample of 20 turkeys sold at the chain’s stores i
> A study was conducted to develop a scale to measure stress in the workplace. Respondents were asked to rate 26 distinct work events. Each event was to be compared with the stress of the first week on the job, which was awarded an arbitrary score of 500.
> A study was conducted to compare the salaries of accounting clerks and data entry operators. One of the hypotheses to be tested is that the variability of salaries among accounting clerks is the same as the variability of salaries of data entry operators
> There are several methods used by people to organize their lives in terms of keeping track of appointments, meetings, and deadlines. Some of these include using a desk calendar, using informal notes of scrap paper, keeping them “in your head,” using a da
> A study is conducted to estimate the average difference in bus ridership for a large city during the morning and afternoon rush hours. The transit authority’s analyst randomly selects nine buses because of the variety of routes they rep
> Suppose a large insurance company wants to estimate the difference between the average amount of term life insurance purchased per family and the average amount of whole life insurance purchased per family. To obtain an estimate, one of the companyâ
> Test the following hypotheses by using the given data. Let alpha = .05.
> How much experience do supply-chain transportation managers have in their field? Suppose in an effort to estimate this, 41 supply-chain transportation managers are surveyed and asked how many years of managerial experience they have in transportation. Su
> Use the following data to construct a 99% confidence interval to estimate p1 – p2.
> Test the following hypotheses by using the given data and alpha equal to .05. H0: p1 − p2 = 0 Ha: p1 − p2 ≠0
> Use the following data to construct a 99% confidence interval to estimate D. Assume the differences are normally distributed in the population.
> Suppose you own a plumbing repair business and employ 15 plumbers. You are interested in estimating the difference in the average number of calls completed per day between two of the plumbers. A random sample of 40 days of plumber A’s work results in a s
> The following data have been gathered from two related samples. The differences are assumed to be normally distributed in the population. Use these data and alpha of .01 to test the following hypotheses. H0: D = 0 Ha: D < 0 n = 21, d̅ =−1.16, sd = 1.01
> Construct a 95% confidence interval to estimate μ1 – μ2 by using the following data. Assume the populations are normally distributed.
> The following data come from independent samples drawn from normally distributed populations. Use these data to test the following hypotheses. Let the Type I error rate be .05. H0: μ1 − μ2 = 0 Ha: Î&fra
> Use the following data to construct a 98% confidence interval to estimate the difference between μ1 and μ2.
> Test the following hypotheses with the data given. Let α = .10. H0: μ1 − μ2 = 0 Ha: μ1 − μ2 ≠0
> According to the General Accounting Office of the U.S. government, the average age of a male federal worker is 43.6 years and that of a male worker in the nonfederal sector is 37.3 years. Is there any difference in the variation of ages of men in the fed
> Suppose a company from the United States does considerable business in the city of Johannesburg, South Africa, and wishes to establish a per diem rate for employee travel to that city. The company researcher is assigned this task, and in an effort to det
> One recent study showed that the average annual amount spent by an East Coast household on frankfurters was $23.84 compared with an average of $19.83 for West Coast households. Suppose a random sample of 11 East Coast households showed that the standard
> How long are resale houses on the market? One survey by the Houston Association of Realtors reported that in Houston, resale houses are on the market an average of 112 days. Of course, the length of time varies by market. Suppose random samples of 13 hou
> Suppose the data shown here are the results of a survey to investigate gasoline prices. Ten service stations were selected randomly in each of two cities and the figures represent the prices of a gallon of unleaded regular gasoline on a given day. Use th
> Test the following hypotheses by using the given sample information and α = .05. Assume the populations are normally distributed.
> The Trade Show Bureau conducted a survey to determine why people go to trade shows. The respondents were asked to rate a series of reasons on a scale from 1 to 5, with 1 representing little importance and 5 representing great importance. One of the reaso
> Test the following hypotheses by using the given sample information and α = .01. Assume the populations are normally distributed.
> Many Americans spend time worrying about paying their bills. A survey by Fleishman Hilliard Research for MassMutual discovered that 60% of Americans with kids say that paying bills is a major concern. This proportion compares to 52% of Americans without
> According to a CCH Unscheduled Absence survey, 9% of small businesses use telecommuting of workers in an effort to reduce unscheduled absenteeism. This proportion compares to 6% for all businesses. Is there really a significant difference between small b
> A large production facility uses two machines to produce a key part for its main product. Inspectors have expressed concern about the quality of the finished product. Quality-control investigation has revealed that the key part made by the two machines i
> Companies that recently developed new products were asked to rate which activities are most difficult to accomplish with new products. Options included such activities as assessing market potential, market testing, finalizing the design, developing a bus
> The marketing director of a large department store wants to estimate the average number of customers who enter the store every 5 minutes. She randomly selects 5-minute intervals and counts the number of arrivals at the store. She obtains the figures 58,
> Does age make a difference in the amount of savings a worker feels is needed to be secure at retirement? A study by CommSciences for Transamerica Asset Management found that .24 of workers in the 25–33 age category feel that $250,000 to $500,000 is enoug
> According to a study conducted by a major computer company, 59% of men and 70% of women say that weight is an extremely/very important factor in purchasing a laptop computer. Suppose this survey was conducted using 374 men and 481 women. Do these data sh
> In each of the following cases, calculate a confidence interval to estimate p1 − p2. a) n1 = 85, n2 = 90, p^1 = .75, p^2 = .67; level of confidence = 90% b) n1 = 1100, n2 = 1300, p^1 = .19, p^2 = .17; level of confidence = 95% c) n1 = 430, n2 = 399, x1 =
> Using the given sample information, test the following hypotheses. a) H0: p1 − p2 = 0 Ha: p1 − p2 ≠0 Note that x is the number in the sample having the characteristic of interest. b) H0: p1 â
> Examine the following data. Assume the variances for the two populations are 22.74 and 26.65, respectively. a) Use the data to test the following hypotheses (( = .02). H0: μ1 − μ2 = 0 Ha: μ1 &ac
> A nationally known supermarket decided to promote its own brand of soft drinks on TV for two weeks. Before the ad campaign, the company randomly selected 21 of its stores across the United States to be part of a study to measure the campaign’s effectiven
> Lawrence and Glover published the results of a study in the Journal of Managerial Issues in which they examined the effects of accounting firm mergers on auditing delay. Auditing delay is the time between a company’s fiscal year-end and the date of the a
> Eleven employees were put under the care of the company nurse because of high cholesterol readings. The nurse lectured them on the dangers of this condition and put them on a new diet. Shown are the cholesterol readings of the 11 employees both before th
> The vice president of marketing brought to the attention of sales managers that most of the company’s manufacturer representatives contacted clients and maintained client relationships in a disorganized, haphazard way. The sales manager
> Some fast-food chains offer a lower-priced combination meal in an effort to attract budget-conscious customers. One chain test-marketed a burger, fries, and drink combination for $1.71. The weekly sales volume for these meals was impressive. Suppose the
> Because of uncertainty in real-estate markets, many homeowners are considering remodeling and constructing additions rather than selling. Probably the most expensive room in the house to remodel is the kitchen, with an average cost of about $23,400. In t
> Construct a 90% confidence interval to estimate D from the following sample information. Assume the differences are normally distributed in the population.
> Construct a 98% confidence interval to estimate D from the following sample information. Assume the differences are normally distributed in the population. d̅ = 40.56, sd = 26.58, n = 22
> Use the data given to test the following hypotheses (α = .05). Assume the differences are normally distributed in the population. H0: D = 0 Ha: D ≠0
> Use the data given and a 1% level of significance to test the following hypotheses. Assume the differences are normally distributed in the population. H0: D = 0 Ha: D > 0
> Some studies have shown that in the United States, men spend more than women buying gifts and cards on Valentine’s Day. Suppose an analyst wants to test this hypothesis by randomly sampling 9 men and 10 women with comparable demographic characteristics f
> Use the following sample information to construct a 90% confidence interval for the difference in the two population means.
> A study was made to compare the costs of supporting a family of four Americans for a year in different foreign cities. The lifestyle of living in the United States on an annual income of $75,000 was the standard against which living in foreign cities was
> What is the difference in average daily hotel room rates between Minneapolis and New Orleans? Suppose we want to estimate this difference by taking hotel rate samples from each city and using a 98% confidence level. The data for such a study follow. Use
> Based on an indication that mean daily car rental rates may be higher for Boston than for Dallas, a survey of eight car rental companies in Boston is taken and the sample mean car rental rate is $47, with a sample standard deviation of $3. Further, suppo
> A valve manufacturer produces a butterfly valve composed of two semicircular plates on a common spindle that is used to permit flow in one direction only. The semicircular plates are supplied by a vendor with specifications that the plates be 2.37 millim
> According to the National Association of Colleges and Employers, the average hourly wage of an undergraduate college student working as a co-op is $17.27 and the average hourly wage of a college student working as an intern is $16.57. Assume that such wa
> Suppose a realtor is interested in comparing the asking prices of midrange homes in Peoria, Illinois, and Evansville, Indiana. The realtor conducts a small telephone survey in the two cities, asking the prices of midrange homes. A random sample of 21 lis
> Suppose you want to determine whether the average values for populations 1 and 2 are different, and you randomly gather the following data. Test your conjecture, using a probability of committing a Type I error of .01. Assume the population variances ar
> Suppose that for years the mean of population 1 has been accepted as the same as the mean of population 2 but that now population 1 is believed to have a greater mean than population 2. Letting α = .05 and assuming the populations have equa
> Use the following data and α = .10 to test the stated hypotheses. Assume x is normally distributed in the populations and the variances of the populations are approximately equal. H0: μ1 − μ2 =
> Use the data given and the eight-step process to test the following hypotheses. H0: μ1 − μ2 = 0 Ha: μ1 − μ2 Use a 1% level of significance, and assume that x is
> Two processes in a manufacturing line are performed manually: operation A and operation B. A random sample of 50 different assemblies using operation A shows that the sample average time per assembly is 8.05 minutes, with a population standard deviation
> Test the following hypotheses of the difference in population means by using the following data (α = .10) and the eight-step process. H0: μ1 − μ2 = 0 Ha: μ1 âˆ
> A manufacturing company produces valves in various sizes and shapes. One particular valve plate is supposed to have a tensile strength of 5 pounds per millimeter (lbs/mm). The company tests a random sample of 42 such valve plates from a lot of 650 valve
> According to a study several years ago by the Personal Communications Industry Association, the average cell phone user earns $62,600 per year. Suppose an analyst believes that the average annual earnings of a cell phone user are lower now, and he sets u
> According to Runzheimer International, the average cost of a domestic trip for business travelers in the financial industry is $1,250. Suppose another travel industry research company takes a random sample of 51 business travelers in the financial indust
> According to the U.S. Bureau of Labor Statistics, the average weekly earnings of a production worker in manufacturing in the United States as of October 2018 was $867.60. Suppose a labor analyst wants to test to determine whether this figure is still acc
> The American Express Retail Index states that the average U.S. household will spend $2,747 on home improvement projects this year. Suppose a large national home improvement company wants to test that figure in the West, theorizing that the average might
> In a recent year, published statistics by Drovers indicated that the average all-fresh retail beef price was $5.83 per pound. Suppose a survey of retailers is conducted this year to determine whether the price of all-fresh retail beef has increased. The
> One survey conducted by RHI Management Resources determined that the Lexus is the favorite luxury car for 25% of CFOs. Suppose a financial management association conducts its own survey of CFOs in an effort to determine whether this figure is correct. Th
> According to the U.S. Census Bureau, the average American generates 4.4 pounds of garbage per day. Suppose we believe that because of recycling and a greater emphasis on the environment, the figure is now lower. To test this notion, we take a random samp
> Downtime in manufacturing is costly and can result in late deliveries, backlogs, failure to meet orders, and even loss of market share. Suppose a manufacturing plant has been averaging 23 minutes of downtime per day for the past several years, but during
> The American Water Works Association reports that, on average, men use between 10 and 15 gallons of water daily to shave when they leave the water running. Suppose the following data are the numbers of gallons of water used in a day to shave by 12 random
> According to SquareFoot.com, the average Class A offiace space in Fort Worth is $31 per square foot. A large real-estate company wants to confirm this figure. The firm conducts a telephone survey of 95 Class A offices in Fort Worth and asks the office ma
> A study of pollutants showed that certain industrial emissions should not exceed 2.5 parts per million. You believe a particular company may be exceeding this average. To test this supposition, you randomly take a sample of nine air tests. The sample ave
> A local company installs natural-gas grills. As part of the installation, a ditch is dug tolay a small natural-gas line from the grill to the main line. On the average, the depth of these lines seems to run about 1 foot. The company claims that the depth
> Use the following data to construct a 99% confidence interval for μ. Assume x is normally distributed. What is the point estimate for μ?
> The Environmental Protection Agency releases figures on urban air soot in selected cities in the United States. For the city of St. Louis, the EPA claims that the average number of micrograms of suspended particles per cubic meter of air is 82. Suppose S
> A national publication reported that a college student living away from home spends, on average, no more than $15 per month on laundry. You believe this figure is too low and want to disprove the publication’s claim. To conduct the test, you randomly sel
> According to Gartner Inc., the second-largest share of the worldwide PC market is held by Hewlett-Packard with 21.7%. Suppose that a market researcher believes that Hewlett-Packard holds a higher share of the market in the western region of the United St
> Suppose the number of beds filled per day in a medium-sized hospital is normally distributed. A hospital administrator tells the board of directors that, on the average, at least 185 beds are filled on any given day. One of the board members believes tha
> A study of MBA graduates by Universum for the American Graduate Survey 1999 revealed that MBA graduates had several expectations of prospective employers beyond their base pay. In particular, according to the study 46% expect a performance-related bonus,
> A financial analyst watched a particular stock for several months. The price of this stock remained fairly stable during this time. In fact, the financial analyst claims that the variance of the price of this stock did not exceed $4 for the entire period
> Life insurance experts have been claiming that the average worker in the city of Cincinnati has no more than $25,000 of personal life insurance. An insurance analyst believes that this is not true and sets out to prove that the average worker in Cincinna
> A computer manufacturer estimates that its line of minicomputers has, on average, 8.4 days of downtime per year. To test this claim, an analyst contacts seven companies that own one of these computers and is allowed to access company computer records. It
> Highway engineers in Ohio are painting white stripes on a highway. The stripes are supposed to be approximately 10 feet long. However, because of the machine, the operator, and the motion of the vehicle carrying the equipment, considerable variation occu
> Brokers generally agree that bonds are a better investment during times of low interest rates than during times of high interest rates. A survey of executives during a time of low interest rates showed that 57% of them had some retirement funds invested
> A random sample of 15 items is taken, producing a sample mean of 2.364 with a sample variance of .81. Assume x is normally distributed and construct a 90% confidence interval for the population mean.
> According to Zero Population Growth, the average urban U.S. resident consumes 3.3 pounds of food per day. Is this figure accurate for rural U.S. residents? Suppose 64 rural U.S. residents are identified by a random procedure and their average consumption
