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 does not vary by more than 16 square inches (the variance). To test this claim, a business analyst randomly took 22 depth measurements at different locations. The sample average depth was 13.4 inches with a standard deviation of 6 inches. Is this enough evidence to reject the company’s claim about the variance? Assume line depths are normally distributed. Let α = .05.
> 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
> 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 unlea
> 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
> 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
> a) Use the data given to test the following hypotheses. H0 : μ = 1200 …..….…… Ha : μ > 1200 x̅ = 1215, n = 113 ……. σ = 100, α = .10 b) Use the p-value to obtain the results. c) Solve for the critical value required to reject the mean.
> According to a Gallup survey two years ago, 32% of American households use a computer or online financial program to manage their money. Suppose analysts believe that this figure has increased recently, and they test their theory by randomly sampling 80
> Solve for the value of beta in each of the following problems. a) H0: μ = 130 Ha: μ > 130 n = 75 σ = 12 α = .01 The alternative mean is actually 135. b) H0: p = .44 Ha: p < .44 n = 1095 α = .05 The alternative proportion is actually .42.
> Test the following hypotheses by using the information given and the eight-step approach. Let alpha be .01. Assume the population is normally distributed. H0: σ2 = 15.4 Ha: σ2 > 15.4 n = 18 s2 = 29.6
> For each of the following problems, use the eight-step approach to test the hypotheses. a) H0: p = .28 Ha: p > .28 n = 783 x = 230 α = .10 b) H0: p = .61 Ha: p ≠ .61 n = 401 p^ = .56 α = .05
> Use the information given and the eight-step approach to test the hypotheses. Let α = .05. Assume that the population is normally distributed. H0: μ = 7.82 Ha: μ < 7.82 n = 17 x̅ = 7.01 s = 1.69
> Use the information given and the eight-step approach to test the hypotheses. Let α = .01. H0: μ = 36 Ha: μ ≠ 36 n = 36 x̅ = 38.4 σ = 5.93
> A Harris poll was taken to determine which of 13 major industries are doing a good job of serving their customers. Among the industries rated most highly by Americans for serving their customers were computer hardware and software companies, car manufact
> The New York Stock Exchange recently reported that the average age of a female shareholder is 44 years. A broker in Chicago wants to know whether this figure is accurate for the female shareholders in Chicago. The broker secures a master list of sharehol
> If a random sample of 41 items produces x̅ = 128.4 and s = 20.6, what is the 98% confidence interval for μ? Assume x is normally distributed for the population. What is the point estimate?
> An alternative hypothesis is that p < .65. To test this hypothesis, a random sample of size 360 is taken. What is the probability of committing a Type II error if α = .05 and the alternative proportion is as follows? a) pa = .60 b) pa = .55 c) pa = .50
> Suppose a hypothesis states that the mean is exactly 50. If a random sample of 35 items is taken to test this hypothesis, what is the value of β if the population standard deviation is 7 and the alternative mean is 53? Use α = .01
> Use the data given to test the following hypotheses. Assume the data are normally distributed in the population. H0 : μ = 7.48 ……………… Ha : μ < 7.48 x̅ = 6.91, n = 24 ……… σ = 1.21, α = .01
> For Problem 9.38, use α = .05 and solve for the probability of committing a Type II error for the following possible true alternative means. a) μa = 98.5 b) μa = 98 c) μa = 97 d) μa = 96 e) What happens to the probability of committing a Type II error as
> Suppose a null hypothesis is that the population mean is greater than or equal to 100. Suppose further that a random sample of 48 items is taken and the population standard deviation is 14. For each of the following α values, compute the probability of c
> A company produces industrial wiring. One batch of wiring is specified to be 2.16 centimeters (cm) thick. A company inspects the wiring in seven locations and determines that, on the average, the wiring is about 2.16 cm thick. However, the measurements v
> A savings and loan averages about $100,000 in deposits per week. However, because of the way pay periods fall, seasonality, and erratic fluctuations in the local economy, deposits are subject to a wide variability. In the past, the variance for weekly de
> A manufacturing company produces bearings. One line of bearings is specified to be 1.64 centimeters (cm) in diameter. A major customer requires that the variance of the bearings be no more than .001 cm2. The producer is required to test the bearings befo
> Previous experience shows the variance of a given process to be 14. Business analysts are testing to determine whether this value has changed. They gather the following dozen measurements of the process. Use these data and α = .05 to test t
> Test each of the following hypotheses by using the given information. Assume the populations are normally distributed. a) H0: σ2 = 20 Ha: σ2 > 20 α = .05, n = 15, s2 = 32 b. H0: σ2 = 8.5 Ha: σ2 ≠ 8.5 α = .10, n = 22, s2 = 17 c) H0: σ2 = 45 Ha: σ2 < 45 α
> Assuming x is normally distributed, use the following information to compute a 90% confidence interval to estimate μ.
> A random sample of size 39 is taken from a population of 200 members. The sample mean is 66 and the population standard deviation is 11. Construct a 96% confidence interval to estimate the population mean. What is the point estimate of the population mea
> 1. A researcher wants to estimate the difference in the means of two populations. A random sample of 40 items from the first population results in a sample mean of 433 with a population standard deviation of 112. A random sample of 50 items from the seco
> 21. A researcher is testing a hypothesis of a single mean. The critical z value for ( = .05 and a two-tailed test is ± 1.96. The observed z value from sample data is -1.91. The decision made by the researcher based on this information is to _____________
> 11. Power is equal to _______________. 12. Whenever hypotheses are established such that the alternative hypothesis is directional, then the researcher is conducting a _______________-tailed test. 13. A _______________-tailed test is non-directional. 14.
> 1. The first step in testing a hypothesis is to establish a(n) _______________ hypothesis and a(n) _______________ hypothesis. 2. In testing hypotheses, the researcher initially assumes that the _______________ hypothesis is true. 3. The region of the di
> 41. The observed value of chi-square in problem 39 is ______________________. 42. The decision reached for problem 39 is _______________. 43. The null hypothesis for a test is H0: ( = 30. The population standard deviation is known to be 0.63. A one-taile
> 31. A political scientist want to statistically test the null hypothesis that her candidate for governor is currently carrying at least 57% of the vote in the state. She has her assistants randomly sample 550 eligible voters in the state by telephone and
> 23. Suppose we want to construct a confidence interval to estimate a population variance. A sample variance is computed from a sample of 14 items. To construct a 95% confidence interval, the chi-square table values are _______________ and _______________
> 11. The t test was developed by _______________. 12. In order to find values in the t distribution table, you must convert the sample size or sizes to _______________. 13. The table t value associated with 10 degrees of freedom and used to compute a 95%
> 13. In conducting multiple comparisons with unequal sample sizes with techniques presented in chapter 11 of the text, you would use which procedure? __________________ 14. Sup1pose the following data are taken as samples from three populations and that a
> 1. A plan for testing hypotheses in which the researcher either controls or manipulates one or more variables is called a(n) ______________________________________. 2. A variable that is either controlled or manipulated is called a(n) ___________________
> 33. The confidence interval computed for the problem in question 29 is _______________. 34. A researcher is interested in estimating the difference in two populations proportions. A sample of 1000 from each population results in sample proportions of .61
> 21. A researcher wants to conduct a before/after study on 13 subjects to determine if a treatment results in higher scores. The hypotheses are: Ho: D = 0 Ha: D Scores are obtained on the subjects both before and after the treatment. After subtracting th
> 11. Using the information from question 9, the observed value of z is _______________. 12. Using the results determined in question 10 and 11, the decision is to _______________ the null hypothesis. 13. A researcher is interested in testing to determine
> 1. When a statistic taken from the sample is used to estimate a population parameter, it is called a(n) _______________ estimate. 2. When a range of values is used to estimate a population parameter, it is called a(n) _______________ estimate. 3. The z v
> The furniture division of International Woodworking purchases timber and makes tables, chairs, and other wood furniture. Most of the timber is purchased from the Port Angeles Mill, also a division of International Woodworking. The furniture division and
> Prem International has two large subsidiaries, Oil and Chemical. Oil is an oil-refining entity, and its main product is petrol. Chemical produces and sells a variety of chemical products. Chemical owns a polystyrene processing plant next to Oilâ
