Fowle Marketing Research, Inc., bases charges to a client on the assumption that telephone surveys can be completed in a mean time of 15 minutes or less. If a longer mean survey time is necessary, a premium rate is charged. A sample of 35 surveys provided the survey times shown in the file Fowle. Based upon past studies, the population standard deviation is assumed known with σ = 4 minutes. Is the premium rate justified? a. Formulate the null and alternative hypotheses for this application. b. Compute the value of the test statistic. c. What is the p-value? d. At α = .01, what is your conclusion?
> Re-solve problem 20 above using a simple exponential smoothing model with =.8, and with a 2-period moving average model. Which model is best?
> Given the data shown below, use α = .1 and β = .2 to create a trend enhanced smoothing based forecast for period 6. Assume that FIT1 = 20 and T1 = 3.
> Given the series of demand data below a. Calculate the forecasts for periods 7 through 11 using moving average models with n=2, n=4, and n=6. b. Calculate the Bias and MAD for each set of forecasts. Which moving average model is best?
> Use the Excel spreadsheet that accompanies this Supplement to evaluate different forecasting models using the ice cream sales data. a. Which model, time series regression, causal regression using temperature, or trend enhanced exponential smoothing, give
> Assume that the following demands vary according a four period seasonal cycle. a. Compute the seasonal indexes using the average demand in each cycle as the base. b. Compute the seasonal indexes using regression estimates as the base. c. How do the answ
> Many supply managers use a monthly reported survey result known as the purchasing managers' index (PMI) as a leading indicator to forecast future sales for their businesses. Suppose that the PMI and your business sales data for the last 10 months are the
> Wamaco Corporation uses the same simple exponential smoothing forecasting model for all of its products. The model has yielded the following weekly forecasts: a. What value of α is Wamaco Corp. using in its forecasting model? b. Calculate
> Calculate the slope and intercept for the data in the question 1 using simple linear regression. You may want to use an Excel spreadsheet to check your answer.
> Repeat problem 13 using (=.4 and β =.8. Which model gives a better approximation of the demand pattern for periods 1 through 6?
> Given the data shown below, use (=.2 and β =.4 to create trend enhanced smoothing based forecasts for periods 7, 8, and 9. Assume that FIT1 = 22 and T1 = 7.83.
> The quality inspectors at Windows Inc. visually inspect each sheet of 4 ft × 8 ft glass when it is through with the annealing process. They record all of the defects onto a form. The defects that have been found this week are given in the ta
> The time students entered the classroom of OM 390, Introductory Operations Management, was recorded by the professor in the table below for five class meetings. Create and analyze a histogram of these data. Please note that a negative time means that the
> One of the biggest changes in higher education in recent years has been the growth of online universities. The Online Education Database is an independent organization whose mission is to build a comprehensive list of the top accredited online colleges.
> The following results come from two independent random samples taken of two populations. Sample 1 ………………………… Sample 2 n1 = 50 …………………………….. n2 = 35 x̅ 1 = 13.6 …………………………. x̅2 = 11.6 σ1 = 2.2 …………………………….. σ 2 = 3.0 a. What is the point estimate of the
> Consider the following hypothesis test: H0: µ ≥ 20 Ha: µ < 20 A sample of 50 provided a sample mean of 19.4. The population standard deviation is 2. a. Compute the value of the test statistic. b. What is the p-value? c. Using α = .05, what is your conclu
> Suppose a new production method will be implemented if a hypothesis test supports the conclusion that the new method reduces the mean operating cost per hour. a. State the appropriate null and alternative hypotheses if the mean cost for the current produ
> Carpetland salespersons average $8000 per week in sales. Steve Contois, the firm’s vice president, proposes a compensation plan with new selling incentives. Steve hopes that the results of a trial selling period will enable him to conclude that the compe
> The label on a 3-quart container of orange juice states that the orange juice contains an average of 1 gram of fat or less. Answer the following questions for a hypothesis test that could be used to test the claim on the label. a. Develop the appropriate
> According to the National Beer Wholesalers Association, U.S. consumers 21 years and older consumed 26.9 gallons of beer and cider per person during 2017. A distributor in Milwaukee believes that beer and cider consumption are higher in that city. A sampl
> Consider the following hypothesis test. H0: µ = 20 Ha: µ ≠ 20 A sample of 200 items will be taken and the population standard deviation is σ = 10. Use α = .05. Compute the probability of making a Type II error if the population mean is: a. µ = 18.0 b. µ
> Consider the following hypothesis test. H0: µ ≥ 10 Ha: µ < 10 The sample size is 120 and the population standard deviation is assumed known with σ = 5. Use α = .05. a. If the population mean is 9, what is the probability that the sample mean leads to the
> The American Association of Individual Investors conducts a weekly survey of its members to measure the percent who are bullish, bearish, and neutral on the stock market for the next six months. For the week ending November 7, 2012, the survey results sh
> One of the reasons health care costs have been rising rapidly in recent years is the increasing cost of malpractice insurance for physicians. Also, fear of being sued causes doctors to run more precautionary tests (possibly unnecessary) just to make sure
> The average annual premium for automobile insurance in the United States is $1503. The following annual premiums ($) are representative of the website’s findings for the state of Michigan. Assume the population is approximately normal
> Eagle Outfitters is a chain of stores specializing in outdoor apparel and camping gear. They are considering a promotion that involves mailing discount coupons to all their credit card customers. This promotion will be considered a success if more than 1
> According to the University of Nevada Center for Logistics Management, 6% of all merchandise sold in the United States gets returned. A Houston department store sampled 80 items sold in January and found that 12 of the items were returned. a. Construct a
> In 2018, RAND Corporation researchers found that 71% of all individuals ages 66 to 69 are adequately prepared financially for retirement. Many financial planners have expressed concern that a smaller percentage of those in this age group who did not comp
> Last year, 46% of business owners gave a holiday gift to their employees. A survey of business owners conducted this year indicates that 35% plan to provide a holiday gift to their employees. Suppose the survey results are based on a sample of 60 busines
> What percentage of the population live in their state of birth? According to the U.S. Census Bureau’s 2014 American Community Survey, the figure ranges from 25% in Nevada to 78.7% in Louisiana. The average percentage across all states and the District of
> A study by Consumer Reports showed that 64% of supermarket shoppers believe supermarket brands to be as good as national name brands. To investigate whether this result applies to its own product, the manufacturer of a national name-brand ketchup asked a
> The U.S. Bureau of Labor Statistics reports that 11.3% of U.S. workers belonged to unions in 2013. Suppose a sample of 400 U.S. workers is collected in 2018 to determine whether union efforts to organize have increased union membership. a. Formulate the
> Consider the following hypothesis test: H0: p ≥ .75 Ha: p < .75 A sample of 300 items was selected. Compute the p-value and state your conclusion for each of the following sample results. Use α = .05. a. p̅ = .68 c. p̅ = .70 b. p̅ = .72 d. p̅ = .77
> Consider the following hypothesis test: H0: p = .20 Ha: p ≠ .20 A sample of 400 provided a sample proportion p = .175. a. Compute the value of the test statistic. b. What is the p-value? c. At α = .05, what is your conclusion? d. What is the rejection ru
> Joan’s Nursery specializes in custom-designed landscaping for residential areas. The estimated labor cost associated with a particular landscaping proposal is based on the number of plantings of trees, shrubs, and so on to be used for t
> The mean cost of a meal for two in a mid-range restaurant in Tokyo is $40 (Numbeo.com website). How do prices for comparable meals in Hong Kong compare? The file HongKongMeals contains the costs for a sample of 42 recent meals for two in Hong Kong mid-ra
> The Onsure.com website reports that the mean annual premium for automobile insurance in the United States was $1503 in March 2014. Being from Pennsylvania at that time, you believed automobile insurance was cheaper there and decided to develop statistica
> According to the National Automobile Dealers Association, the mean price for used cars is $10,192. A manager of a Kansas City used car dealership reviewed a sample of 50 recent used car sales at the dealership in an attempt to determine whether the popul
> The United States ranks ninth in the world in per capita chocolate consumption; Forbes reports that the average American eats 9.5 pounds of chocolate annually. Suppose you are curious whether chocolate consumption is higher in Hershey, Pennsylvania, the
> The time married men with children spend on child care averages 6.4 hours per week. You belong to a professional group on family practices that would like to do its own study to determine if the time married men in your area spend on child care per week
> A production line operation is designed to fill cartons with laundry detergent to a mean weight of 32 ounces. A sample of cartons is periodically selected and weighed to determine whether underfilling or overfilling is occurring. If the sample data lead
> On its municipal website, the city of Tulsa states that the rate it charges per 5 CCF of residential water is $21.62. How do the residential water rates of other U.S. public utilities compare to Tulsa's rate? The file ResidentialWater contains the rate p
> A shareholders’ group, in lodging a protest, claimed that the mean tenure for a chief executive office (CEO) was at least nine years. A survey of companies reported in The Wall Street Journal found a sample mean tenure of x̅ = 7.27 years for CEOs with a
> According to the Vivino website, the mean price for a bottle of red wine that scores 4.0 or higher on the Vivino Rating System is $32.48. A New England–based lifestyle magazine wants to determine if red wines of the same quality are less expensive in Pro
> Consider the following hypothesis test: H0: µ = 100 Ha: µ ≠ 100 A sample of 65 is used. Identify the p-value and state your conclusion for each of the following sample results. Use α = .05. a. x̅ = 103 and s = 11.5 b. x̅ = 96.5 and s = 11.0 c. x̅ = 102 a
> Consider the following hypothesis test: H0: µ ≥ 45 Ha: µ < 45 A sample of 36 is used. Identify the p-value and state your conclusion for each of the following sample results. Use α = .01. a. x̅ = 44 and s = 5.2 b. x̅ = 43 and s = 4.6 c. x̅ = 46 and s = 5
> Older people often have a hard time finding work. AARP reported on the number of weeks it takes a worker aged 55 plus to find a job. The data on number of weeks spent searching for a job contained in the file JobSearch are consistent with the AARP findin
> Consider the following hypothesis test: H0: µ = 18 Ha: µ ≠ 18 A sample of 48 provided a sample mean x = 17 and a sample standard deviation σ = 4.5. a. Compute the value of the test statistic. b. Use the t distribution table (Table 2 in Appendix B) to com
> Consider the following hypothesis test: H0: µ ≤ 12 Ha: µ > 12 A sample of 25 provided a sample mean x = 14 and a sample standard deviation σ = 4.32. a. Compute the value of the test statistic. b. Use the t distribution table (Table 2 in Appendix B) to co
> CCN and ActMedia provided a television channel targeted to individuals waiting in supermarket checkout lines. The channel showed news, short features, and advertisements. The length of the program was based on the assumption that the population mean time
> Annual expenditure for prescription drugs was $838 per person in the Northeast of the country. A sample of 60 individuals in the Midwest showed a per person annual expenditure for prescription drugs of $745. Use a population standard deviation of $300 to
> For a t distribution with 16 degrees of freedom, find the area, or probability, in each region. a. To the right of 2.120 b. To the left of 1.337 c. To the left of −1.746 d. To the right of 2.583 e. Between −2.120 and 2.120 f. Between −1.746 and 1.746
> Costs are rising for all kinds of medical care. The mean monthly rent at assisted-living facilities was reported to have increased 17% over the last five years to $3486. Assume this cost estimate is based on a sample of 120 facilities and, from past stud
> The mean cost to repair the smoke and fire damage that results from home fires of all causes is $11,389 (HomeAdvisor). How does the damage that results from home fires caused by careless use of tobacco compare? The file TobaccoFires provides the cost to
> Studies show that massage therapy has a variety of health benefits and it is not too expensive. A sample of 10 typical one-hour massage therapy sessions showed an average charge of $59. The population standard deviation for a one-hour session is σ = $5.5
> Money reports that the average annual cost of the first year of owning and caring for a large dog in 2017 is $1448. The Irish Red and White Setter Association of America has requested a study to estimate the annual first-year cost for owners of this bree
> In an attempt to assess total daily travel taxes in various cities, the Global Business Travel Association conducted a study of daily travel taxes on lodging, rental car, and meals. The data contained in the file TravelTax are consistent with the finding
> Data were collected on the amount spent by 64 customers for lunch at a major Houston restaurant. These data are contained in the file Houston. Based upon past studies the population standard deviation is known with σ = $6. a. At 99% confidence, what is t
> The manager of an automobile dealership is considering a new bonus plan designed to increase sales volume. Currently, the mean sales volume is 14 automobiles per month. The manager wants to conduct a research study to see whether the new bonus plan incre
> Because of high production-changeover time and costs, a director of manufacturing must convince management that a proposed manufacturing method reduces costs before the new method can be implemented. The current production method operates with a mean cos
> A simple random sample of 60 items resulted in a sample mean of 80. The population standard deviation is σ = 15. a. Compute the 95% confidence interval for the population mean. b. Assume that the same sample mean was obtained from a sample of 120 items
> A simple random sample of 50 items from a population with σ = 6 resulted in a sample mean of 32. a. Provide a 90% confidence interval for the population mean. b. Provide a 95% confidence interval for the population mean. c. Provide a 99% confidence in
> A simple random sample of 40 items resulted in a sample mean of 25. The population standard deviation is σ = 5. a. What is the standard error of the mean, σx? b. At 95% confidence, what is the margin of error?
> An investor wants to select one of seven mutual funds for the coming year. Data showing the percentage annual return for each fund during five typical one-year periods are shown here. The assumption is that one of these five-year periods will occur again
> Many factors influence the retail price of gasoline. The following table shows the average retail price for a gallon of regular grade gasoline for each year from 2014 through 2017 (U.S. Energy Information Administration website). Year Average …………………………
> Samples of size 5 provided the following 20 sample means for a production process that is believed to be in control. a. Based on these data, what is an estimate of the mean when the process is in control? b. Assume that the process standard deviation i
> A manufacturer produces lots of a canned food product. Let p denote the proportion of the lots that do not meet the product quality specifications. An η = 25, c = 0 acceptance sampling plan will be used. a. Compute points on the operating characteristic
> An acceptance sampling plan with n = 15 and c = 1 has been designed with a producer’s risk of .075. a. Was the value of p0 .01, .02, .03, .04, or .05? What does this value mean? b. What is the consumer’s risk associated with this plan if p1 is .25?
> An n = 10, c = 2 acceptance sampling plan is being considered; assume that p0 = .05 and p1 = .20. a. Compute both producer’s and consumer’s risk for this acceptance sampling plan. b. Would the producer, the consumer, or both be unhappy with the proposed
> According to the IRS, taxpayers calling the IRS in 2017 waited 13 minutes on average for an IRS telephone assister to answer. Do callers who use the IRS help line early in the day have a shorter wait? Suppose a sample of 50 callers who placed their calls
> Managers of 1200 different retail outlets make twice-a-month restocking orders from a central warehouse. Past experience shows that 4% of the orders result in one or more errors such as wrong item shipped, wrong quantity shipped, and item requested but n
> An insurance company samples claim forms for errors created by its employees as well as the amount of time it takes to process a claim. a. When the process is in control, the proportion of claims with an error is .033. A p chart has LCL = 0 and UCL = .06
> The following were collected for the Master Blend Coffee production process. The data show the filling weights based on samples of 3-pound cans of coffee. Use these data to construct the xÌ… and R charts. What conclusions can be made about th
> The following are quality control data for a manufacturing process at Kensport Chemical Company. The data show the temperature in degrees centigrade at five points in time during a manufacturing cycle. The company is interested in using control charts to
> Twenty-five samples of size 5 resulted in x̅ = 5.42 and R̅ = 2.0. Compute control limits for the x̅ and R charts, and estimate the standard deviation of the process.
> Product filling weights are normally distributed with a mean of 350 grams and a standard deviation of 15 grams. a. Develop the control limits for the x chart for samples of size 10, 20, and 30. b. What happens to the control limits as the sample size is
> Williams Sonoma is a consumer retail company that sells kitchenware. Williams Sonoma has reported the quantity and product value information for three different glass tumblers in two different years in the table that follows. Compute a weighted aggregate
> The closing price of Walmart stock at the end of its fiscal year (end of January) for five years is given in the following table. The CPI for January of each year is also provided. Deflate the stock price series and comment on the financial performance o
> Actuaries are analysts who specialize in the mathematics of risk. Actuaries often work for insurance companies and are responsible for setting premiums for insurance policies. Below are the median salaries for actuaries and the yearly CPI for four years.
> The operations of seafood restaurant chains such as Red Lobster are sensitive to changes in the price of seafood. Quantity data for a regional seafood chain coupled with price data are in the following table (Statista website). a. Compute a price rela
> The American Institute of Certified Tax Planners reports that the average U.S. CPA works 60 hours per week during tax season. Do CPAs in states that have flat state income tax rates work fewer hours per week during tax season? Conduct a hypothesis test t
> Compute the price relatives for the four stocks making up the Boran index in exercise 20. Use the weighted aggregates of price relatives to compute the January of Year 3 and March of Year 3 Boran indexes. Exercise 20: Boran Stockbrokers, Inc., selects f
> Boran Stockbrokers, Inc., selects four stocks for the purpose of developing its own index of stock market behavior. Prices per share for a Year 1 base period, January of Year 3, and March of Year 3 follow. Base-year quantities are set on the basis of his
> Use the price data in exercise 18 to compute a Paasche index for the shipping cost if Year 5 quantities are 4000, 3000, 7500, and 3000 for the four products, respectively. Exercise 18: Nickerson Manufacturing Company has the following data on quantities
> Nickerson Manufacturing Company has the following data on quantities shipped and unit shipping costs for each of its four products: a. Compute the price relative for each product. b. Compute a weighted aggregate price index that reflects the shipping c
> Nielsen Research provides weekly ratings of nationally broadcast television programs. The mean weekly number of viewers for the 207 prime-time programs broadcast by five major televisions networks (ABC, CBS, FOX, NBC, and CW) for the 2017â€
> A sample of 15 students received the following rankings on midterm and final examinations in a statistics course. Compute the Spearman rank-correlation coefficient for the data and test for a significant correlation with α = .10. What is th
> Course evaluation ratings for four college instructors are shown in the following table. Use α = .05 and test for a significant difference among the rating for these instructors. What is your conclusion?
> A sample of 20 engineers employed with a company for three years has been rank ordered with respect to managerial potential. Some of the engineers attended the company’s management-development course, others attended an off-site managem
> A client wants to determine whether there is a significant difference in the time required to complete a program evaluation with the three different methods that are in common use. The times (in hours) required for each of 18 evaluators to conduct a prog
> The following data are product weights for the same items produced on two different production lines. Test for a difference between the product weights for the two lines. Use α = .05. Line 1 …………………………………………… Line 2 13.6 …………………………………………………. 13.7 13.8 …
> TextRequest reports that adults 18–24 years old send and receive 128 texts every day. Suppose we take a sample of 25–34 year olds to see if their mean number of daily texts differs from the mean for 18–24 year olds reported by TextRequest. a. State the n
> A study was designed to evaluate the weight-gain potential of a new poultry feed. A sample of 12 chickens was used in a six-week study. The weight of each chicken was recorded before and after the six-week test period. The differences between the before
> Twelve homemakers were asked to estimate the retail selling price of two models of refrigerators. Their estimates of selling price are shown in the following table. Use these data and test at the .05 level of significance to determine whether there is a
> According to the National Association of Realtors website (https://www.nar.realtor/sites/default/files/documents/metro-home-prices-q3-2017-single-family-2017-11-02.pdf), the national median sales price for single-family homes was $254,000 in 2018. Assume
> A survey asked the following question: Do you favor or oppose providing tax-funded vouchers or tax deductions to parents who send their children to private schools? Of the 2010 individuals surveyed, 905 favored the proposal, 1045 opposed the proposal, an
> Refer to the Hudson Marine data in exercise 53. a. Deseasonalize the data and use the deseasonalized time series to identify the trend. b. Use the results of part (a) to develop a quarterly forecast for next year based on trend. c. Use the seasonal index
> Refer to the Hudson Marine problem in exercise 53. a. Compute the centered moving average values for this time series. b. Construct a time series plot that also shows the centered moving average and original time series on the same graph. Discuss the dif
> Refer to the Hudson Marine problem in exercise 52. Suppose the quarterly sales values for the seven years of historical data are as follows. a. Use the following dummy variables to develop an estimated regression equation to account for any season and
> Hudson Marine provides boat sales, service, and maintenance. Boat trailers are one of its top sales items. The following table reports the number of trailers sold for the last seven years. a. Construct a time series plot. Does a linear trend appear to
> Refer to the Costello Music Company time series in exercise 49. a. Deseasonalize the data and use the deseasonalized time series to identify the trend. b. Use the results of part (a) to develop a quarterly forecast for next year based on trend. c. Use th
