A hotel installs smoke detectors with adjustable sensitivity in all public guest rooms. (a) State the null and alternative hypotheses. (b) Define Type I and II errors. (c) What are the consequences of each type of error, and to whom?
> There is a 70 percent chance that an airline passenger will check bags. In the next 16 passengers that check in for their flight at Denver International Airport, find the probability that (a) all will check bags; (b) fewer than 10 will check bags; (c) at
> (a) The table shows raw scores on a state civil service exam taken by 24 applicants for positions in law enforcement. Construct a frequency distribution and histogram, using nice (round) bin limits. (b) Describe the distribution and note any unusual feat
> (a) The table shows the number of days on the market for the 36 recent home sales in the city of Sonando Hills. Construct a frequency distribution and histogram, using nice (round) bin limits. (b) Describe the distribution and note any unusual features.
> (a) Make a stem-and-leaf plot for the number of defects per 100 vehicles for these 32 brands. (b) Make a dot plot of the defects data. (c) Describe these two displays. (Hint: Refer to center, variability, and shape.) Defects per 100 Vehicles (alphab
> What kind of survey (mail, telephone, interview, web, direct observation) would you recommend that a small laundry and dry cleaning business use for each of the following purposes, and why? a. To estimate the proportion of customers preferring opening h
> What kind of survey (mail, telephone, interview, web, direct observation) would you recommend for each of the following purposes, and why? What problems might be encountered? a. To estimate the proportion of students at your university who would prefer
> What sources of error might you encounter if you want to know (a) about the dating habits of college men, so you go to a dorm meeting and ask students how many dates they have had in the last year; (b) how often people attend religious services, so you s
> (a) Use Excel to prepare a 2-D pie chart for these web-surfing data. Modify the default colors, fonts, etc., as you judge appropriate to make the display effective. (b) Right-click the chart area, select Chart Type, and change to an exploded 2-D pie char
> (a) Use Excel to prepare a 2-D stacked column chart for television sales by year. Modify the colors, fonts, etc., to make the display effective. (b) Change your graph to a 3-D stacked column chart. Modify the chart if necessary to make it attractive. (c)
> Below are sorted data showing average spending per customer (in dollars) at 74 Noodles & Company restaurants. (a) Construct a frequency distribution. Explain how you chose the number of bins and the bin limits. (b) Make a histogram and describe its a
> (a) Make a stem-and-leaf plot for these 24 observations on the number of customers who used a downtown CitiBank ATM during the noon hour on 24 consecutive workdays. (b) Make a dot plot of the ATM data. (c) Describe these two displays. (Hint: Refer to cen
> Use the sample information x bar = 2.4, σ = 0.15, n = 9 to calculate the following confidence intervals for μ assuming the sample is from a normal population: (a) 90 percent confidence; (b) 95 percent confidence; (c) 99 percent confidence. (d) Describe h
> Which measurement level (nominal, ordinal, interval, ratio) is each of the following variables? Explain. a. Number of hits in Game 1 of the next World Series. b. Baltimore’s standing in the American League East (among fi ve teams). c. Field position of
> (a) Would the measurement level for the data collected from this Microsoft® survey question be nominal, ordinal, interval, or ratio? (b) Would a “6” response be considered twice as good as a â€
> Which measurement level (nominal, ordinal, interval, ratio) is the response to each question? If you think that the level of measurement is ambiguous, explain why. a. How would you describe your level of skill in using Excel? (check one) ❏ Low ❏ Medium
> When Pennsylvania repealed a law that required motorcycle riders to wear helmets, a news headline reported, “Deaths Soar After Repeal of Helmet Law.” After reading the story, Bill said, “But it’s just a correlation, not causation.” Do you agree with Bill
> Which measurement level (nominal, ordinal, interval, ratio) is each of the following variables? Explain. a. Number of passengers on Delta Flight 833. b. Waiting time (minutes) after gate pushback before Delta Flight 833 takes off. c. Brand of cell phone
> What logical or ethical problems do you see in these hypothetical scenarios? a. Dolon Privacy Consultants concludes that its employees are not loyal because a few samples of employee e-mails contained comments critical of the company’s management. b. Ca
> Which measurement level (nominal, ordinal, interval, ratio) is each of the following variables? Explain. a. Number of employees in the Walmart store in Hutchinson, Kansas. b. Number of merchandise returns on a randomly chosen Monday at a Walmart store.
> “Smokers are much more likely to speed, run red lights, and get involved in car accidents than nonsmokers.” (a) Can you think of reasons why this statement might be misleading? Hint: Make a list of six factors that you think would cause car accidents. Is
> A lottery winner told how he picked his six-digit winning number (5-6-8-10-22-39): number of people in his family, birth date of his wife, school grade of his 13-year-old daughter, sum of his birth date and his wife’s, number of years of marriage, and ye
> A study found that radar detector users have lower accident rates, wear their seat belts more, and even vote more than nonusers. (a) Assuming that the study is accurate, do you think there is cause-and- effect? (b) If everyone used radar detectors, would
> Find the interval within which 90 percent of the sample means would be expected to fall, assuming that each sample is from a normal population. a. μ = 100, σ = 12, n = 36 b. μ = 2,000, σ = 150, n = 9 c. μ = 500, σ = 10, n = 25
> A National Health Interview Survey conducted by the U.S. Centers for Disease Control reported that using a cell phone instead of a landline appeared to double a person’s chances of binge drinking. “I guess I’d better give up my cell phone,” said Bob. Whi
> (a) Make a frequency distribution and histogram for the 2007 annual compensation of 40 randomly chosen CEOs (millions of dollars). (b) Describe the shape of the histogram. (c) Identify any unusual values. (Source: www.forbes.com.) 5.33 18.3 24.55 9.
> Using your favorite web browser, enter the search string “business code of ethics.” List five examples of features that a business ethics code should have.
> The U.S. Public Interest Research Group Education Fund, USPIRG, recently published a report titled The Campus Credit Card Trap: A Survey of College Students about Credit Card Marketing. You can find this report and more information about campus credit ca
> (a) The table shows raw scores on a state civil service exam taken by 24 applicants for positions in law enforcement. Construct a frequency distribution and histogram, using nice (round) bin limits. (b) Describe the distribution and note any unusual feat
> (a) The table shows the number of days on the market for the 36 recent home sales in the city of Sonando Hills. Construct a frequency distribution and histogram, using nice (round) bin limits. (b) Describe the distribution and note any unusual features.
> (a) Should the average business school graduate expect to use computers to manipulate data, or is this a job better left to specialists? (b) What problems arise when an employee is weak in quantitative skills? Based on your experience, is that common?
> Give an example of how statistics might be useful to the person in the scenario. a. A personnel executive is examining job turnover by gender in different restaurants in a fast food chain. b. An intranet manager is studying e-mail usage rates by employe
> Give an example of how statistics might be useful to the person in the scenario. a. An auditor is looking for inflated broker commissions in stock transactions. b. An industrial marketer is representing her firm’s compact, new low-power OLED screens to t
> The Scottsdale fire department aims to respond to fire calls in 4 minutes or less, on average. State the hypotheses you would use if you had reason to believe that the fire department’s claim is not being met. Hint: Remember that sample data are used as
> The mean life of a certain computer hard disk in continual use is 8 years. (a) How long a warranty should be offered if the vendor wants to ensure that not more than 10 percent of the hard disks will fail within the warranty period? (b) Not more than 20
> Repeat the previous exercise, using α = .05. For each true value of μ, is the power higher or lower? Previous exercise: For a certain wine, the mean pH (a measure of acidity) is supposed to be 3.50 with a known standard deviation of σ = .10. The qualit
> What is the consequence of a false positive in a weekly inspection of a nuclear plant’s cooling system? Hint: The null hypothesis is the status quo (things are OK).
> For a certain wine, the mean pH (a measure of acidity) is supposed to be 3.50 with a known standard deviation of σ = .10. The quality inspector examines 25 bottles at random to test whether the pH is too low, using a left-tailed test at α = .01. (a) What
> Repeat the previous exercise, using α = .05. For each true value of π, is the power higher or lower? Previous exercise: A quality expert inspects 400 items to test whether the population proportion of defectives exceeds .03, using a right-tailed test a
> A quality expert inspects 400 items to test whether the population proportion of defectives exceeds .03, using a right-tailed test at α = .10. (a) What is the power of this test if the true proportion of defectives is π = .04? (b) If the true proportion
> A coin was flipped 12 times and came up heads 10 times. (a) Would we be justified in assuming that the sample proportion p is normally distributed? Explain. (b) Calculate a p-value for the observed sample outcome, using the normal distribution. At the .0
> The recent default rate on all student loans is 5.2 percent. In a recent random sample of 300 loans at private universities, there were 9 defaults. (a) Does this sample show sufficient evidence that the private university loan default rate is below the r
> To encourage telephone efficiency, a catalog call center issues a guideline that at least half of all telephone orders should be completed within 2 minutes. Subsequently, a random sample of 64 telephone calls showed that only 24 calls lasted 2 minutes or
> To combat antibiotic resistance, the Quality Improvement Consortium recommends a throat swab to confirm strep throat before a physician prescribes antibiotics to children under age 5. In a random sample of 60 children who received antibiotics for throat
> In a hospital’s shipment of 3,500 insulin syringes, 14 were unusable due to defects. (a) At α = .05, is this sufficient evidence to reject future shipments from this supplier if the hospital’s quality standard requires 99.7 percent of the syringes to be
> Between 2 a.m. and 4 a.m. at an all-night pizza parlor, the mean time between arrival of telephone pizza orders is 20 minutes. (a) Find the median wait for pizza order arrivals. (b) Explain why the median is not equal to the mean. (c) Find the upper quar
> Calculate the test statistic and p-value for each sample. a. H0: π < .60 versus H1: π > .60, α = .05, x = 56, n = 80 b. H0: π = .30 versus H1: π ≠ .30, α = .05, x = 18, n = 40 c. H0: π > .10 versus H1: π < .10, α = .01, x = 3, n = 100
> Interpret each p-value in your own words: a. p-value = .387, H0: π > .20, H1: π < .20, α = .10 b. p-value = .043, H0: π < .90, H1: π > .90, α = .05 c. p-value = .0012, H0: π = .50, H1: π ≠ .50, α = .01
> At Oxnard University, a sample of 18 senior accounting majors showed a mean cumulative GPA of 3.35 with a standard deviation of 0.25. (a) At α = .05 in a two-tailed test, does this differ significantly from 3.25 (the mean GPA for all business school seni
> The average age of a part-time seasonal employee at a Vail Resorts ski mountain has historically been 37 years. A random sample of 50 part-time seasonal employees in 2010 had a sample mean age of 38.5 years with a sample standard deviation equal to 16 ye
> The average weight of a package of rolled oats is supposed to be at least 18 ounces. A sample of 18 packages shows a mean of 17.78 ounces with a standard deviation of 0.41 ounce. (a) At the 5 percent level of significance, is the true mean smaller than t
> Which type of data (cross-sectional or time series) is each variable? a. Scores of 50 students on a midterm accounting exam last semester. b. Bob’s scores on 10 weekly accounting quizzes last semester. c. Average score by all takers of the state’s CPA e
> Sarah and Bob share a 1,000-minute cell phone calling plan. (a) Make a stacked dot plot to compare the lengths of cell phone calls by Sarah and Bob during the last week. (b) Describe what the dot plots tell you. Sarah’s calls: 1, 1, 1, 1, 2, 3, 3, 3, 5,
> Noodles & Company is interested in testing whether their new menu design helps reduce the average order time for their customers. Suppose that the average order time prior to the introduction of their new menu was 1.2 minutes. Write the hypotheses for a
> A manufacturer claims that its compact fluorescent bulbs contain an average of 2.5 mg of mercury. Write the hypotheses for a two-tailed test, using the manufacturer’s claim about the mean as the null hypothesis.
> A passenger metal detector at Chicago’s Midway Airport gives an alarm 0.5 time a minute. (a) Find the median waiting time until the next alarm. (b) Find the first quartile of waiting time before the next alarm. (c) Find the 30th percentile waiting time u
> In U.S. hospitals, the average length of stay (LOS) for a diagnosis of pneumonia is 137 hours with a standard deviation of 25 hours. The LOS (in hours) for a sample of 12 pneumonia patients at Santa Theresa Memorial Hospital is shown below. In a two-tail
> pH is a measure of acidity that winemakers must watch. A “healthy wine” should have a pH in the range 3.1 to 3.7. The target standard deviation is σ = 0.10 (i.e., σ2 = 0.01). The pH measurements f
> A sample of size n = 19 has variance s2 = 1.96. At α = .05 in a right-tailed test, does this sample contradict the hypothesis that σ2 = 1.21?
> A sample of size n = 10 has variance s2 = 16. At α = .10 in a two-tailed test, does this sample contradict the hypothesis that σ2 = 24?
> A sample of size n = 15 has variance s2 = 35. At α = .01 in a left-tailed test, does this sample contradict the hypothesis that σ2 = 50?
> Perfect pitch is the ability to identify musical notes correctly without hearing another note as a reference. The probability that a randomly chosen person has perfect pitch is .0005. (a) If 20 students at Julliard School of Music are tested, and 2 are f
> BriteScreen, a manufacturer of 19-inch LCD computer screens, requires that on average 99.9 percent of all LCDs conform to its quality standard. In a day’s production of 2,000 units, 4 are defective. (a) Assuming this is a random sample, is the standard b
> A poll of 702 frequent and occasional fliers found that 442 respondents favored a ban on cell phones in flight, even if technology permits it. At α = .05, can we conclude that more than half the sampled population supports a ban?
> What is the consequence of a false negative in an inspection of your car’s brakes? Hint: The null hypothesis is the status quo (things are OK).
> In a recent survey, 10 percent of the participants rated Pepsi as being “concerned with my health.” PepsiCo’s response included a new “Smart Spot” symbol on its products that meet certain nutrition criteria, to help consumers who seek more healthful eati
> Find each uniform continuous probability and sketch a graph showing it as a shaded area. a. P (X < 10) for U (0, 50) b. P (X > 500) for U (0, 1,000) c. P (25 < X < 45) for U (15, 65)
> May normality of the sample proportion p be assumed? Show your work. a. H0: π = .30 versus H1: π ≠ .30, n = 20 b. H0: π = .05 versus H1: π ≠ .05, n = 50 c. H0: π = .10 versus H1: π ≠ .10, n = 400
> Calculate the test statistic and p-value for each sample. A. H0: π = .20 versus H1: π ≠ .20, α 5 .025, p = .28, n = 100 B. H0: π < .50 versus H1: π > .50, α 5 .025, p = .60, n = 90 C. H0: π < .75 versus H1: π > .75, α 5 .10, p = .82, n = 50
> In 2008, a small dealership leased 21 Suburu Outbacks on 2-year leases. When the cars were returned in 2010, the mileage was recorded (see below). Is the dealer’s mean significantly greater than the national average of 30,000 miles for
> The number of entrees purchased in a single order at a Noodles & Company restaurant has had an historical average of 1.60 entrees per order. On a particular Saturday afternoon, a random sample of 40 Noodles orders had a mean number of entrees equal to 1.
> According to J.D. Power & Associates, the mean purchase price of a smartphone device (such as an iPhone or Blackberry) in 2008 was $216. In 2009, a random sample of 20 business managers who owned a smartphone device showed a mean purchase price of $209 w
> The manufacturer of an airport baggage scanning machine claims it can handle an average of 530 bags per hour. At α = .05 in a left-tailed test, would a sample of 16 randomly chosen hours with a mean of 510 and a standard deviation of 50 indicate that the
> Use Excel to find the p-value for each test statistic. a. Right-tailed test, t = 11.677, n = 13 b. Left-tailed test, t = 22.107, n = 5 c. Two-tailed test, t = 21.865, n = 34
> Find the p-value using Excel (not Appendix D): a. t = 1.457, d.f. = 14, right-tailed test b. t = 2.601, d.f. = 8, two-tailed test c. t = 21.847, d.f. = 22, left-tailed test
> Find the tcalc test statistic for each hypothesis test. A. x bar = 347, μ0 = 349, s = 1.8, n = 9 B. x bar = 45, μ0 = 50, s = 12, n = 16 C. x bar = 4.103, μ0 = 4.004, s = 0.245, n = 25
> Find the critical value of Student’s t for each hypothesis test. a. Two-tailed test, n = 18, a = .05 b. Right-tailed test, n = 15, a = .10 c. Left-tailed test, n = 31, a = .01
> Between 11 p.m. and midnight on Thursday night, Mystery Pizza gets an average of 4.2 telephone orders per hour. (a) Find the median waiting time until the next telephone order. (b) Find the upper quartile of waiting time before the next telephone order.
> Find the critical value of Student’s t for each hypothesis test. a. 10 percent level of significance, two-tailed test, n = 21 b. 1 percent level of significance, right-tailed test, n = 9 c. 5 percent level of significance, left-tailed test, n = 28
> Find the tcalc test statistic for each hypothesis test. A. x bar = 14.7, μ0 = 13.0, s = 1.8, n = 12 B. x bar = 241, μ0 = 250, s = 12, n = 8 C. x bar = 2,102, μ0 = 2,000, s = 242, n = 17
> The lifespan of xenon metal halide arc-discharge bulbs for aircraft landing lights is normally distributed with a mean of 3,000 hours and a standard deviation of 500 hours. If a new ballast system shows a mean life of 3,515 hours in a test on a sample of
> Procyon Mfg. produces tennis balls. Weights are supposed to be normally distributed with a mean of 2.035 ounces and a standard deviation of 0.002 ounce. A sample of 25 tennis balls shows a mean weight of 2.036 ounces. At α = .025 in a right-tailed test,
> Determine the p-value for each test statistic. a. Right-tailed test, z = +1.34 b. Left-tailed test, z = -2.07 c. Two-tailed test, z = -1.69
> Green Beam Ltd. claims that its compact fluorescent bulbs average no more than 3.50 mg of mercury. A sample of 25 bulbs shows a mean of 3.59 mg of mercury. (A) Write the hypotheses for a right-tailed test, using Green Beam’s claim as the null hypothesis
> Find the zcalc test statistic for each hypothesis test. A. x bar = 423, μ0 = 420, σ = 6, n = 9 B. x bar = 8330, μ0 = 8,344, σ = 48, n = 36 C. x bar = 3.102, μ0 = 3.110, σ = .250, n = 25
> Use Excel to find the critical value of z for each hypothesis test. a. α = .05, two-tailed test b. α = .10, right-tailed test c. α = .01, left-tailed test
> Use Excel to find the critical value of z for each hypothesis test. a. 10 percent level of significance, two-tailed test b. 1 percent level of significance, right-tailed test c. 5 percent level of significance, left-tailed test
> Find the zcalc test statistic for each hypothesis test. A. x bar = 242, μ0 = 230, σ = 18, n = 20 B. x bar = 3.44, μ0 = 3.50, σ = 0.24, n = 40 C. x bar = 21.02, μ0 = 20.00, σ = 2.52, n = 30
> The time it takes a ski patroller to respond to an accident call has an exponential distribution with an average equal to 5 minutes. (a) In what time will 90 percent of all ski accident calls be responded to? (b) If the ski patrol would like to be able t
> The Ball Corporation’s aluminum can manufacturing facility in Ft. Atkinson, Wisconsin, wants to use a sample to perform a two-tailed test to see whether the mean incoming metal thickness is at the target of 0.2731 mm. A deviation in either direction woul
> Sketch a diagram of the decision rule for each pair of hypotheses. a. H0: μ >80 versus H1: μ < 80 b. H0: μ = 80 versus H1: μ ≠ 80 c. H0: μ < 80 versus H1: μ > 80
> The average age of a part-time seasonal employee at a Vail Resorts ski mountain has historically been 37 years. State the hypotheses one would use to test if this average has decreased since the last season.
> If you repeated a hypothesis test 1,000 times (in other words, 1,000 different samples from the same population), how many times would you expect to commit a Type I error, assuming the null hypothesis were true, if (a) α = .05; (b) α = .01; or (c) α = .0
> Construct a confidence interval for μ assuming that each sample is from a normal population. a. x bar = 14, σ = 4, n = 5, 90 percent confidence b. x bar = 37, σ = 5, n = 15, 99 percent confidence c. x bar = 121, σ = 15, n = 25, 95 percent confidence
> The fuel economy of a 2011 Lexus RX 350 2WD 6 cylinder 3.5 L automatic 5-speed using premium fuel is a normally distributed random variable with a mean of μ = 25.0 MPG and a standard deviation of σ = 1.25 MPG. (a) What is the standard error of X , the me
> The fat content of a pouch of Keebler Right Bites© Fudge Shoppe© Mini-Fudge Stripes is normally distributed with a mean of 3.50 grams. Assume a known standard deviation of 0.25 gram. (a) What is the standard error of X , the mean weight from a random sam
> (a) Find the standard error of the mean for each sampling situation (assuming a normal population). (b) What happens to the standard error each time you quadruple the sample size? a. σ = 24, n = 9 b. σ = 24, n = 36 c. σ = 24, n = 144
> Find the 90 percent confidence interval for the standard deviation of gasoline mileage mpg for these 16 San Francisco commuters driving hybrid gas-electric vehicles. 38.8 48.9 28.5 40.0 38.8 29.2 29.1 38.5 34.4 46.1 51.8 30.7 36.9 25.6 42.7 38.3
> A pediatrician’s records showed the mean height of a random sample of 25 girls at age 12 months to be 29.530 inches with a standard deviation of 1.0953 inches. Construct a 95 percent confidence interval for the population variance. (Data are from a proje
> At a certain Noodles & Company restaurant, customers arrive during the lunch hour at a rate of 2.8 per minute. What is the probability that (a) at least 30 seconds will pass before the net customer walks in; (b) no more than 15 seconds; (c) more than 1 m
> The weights of 20 oranges (in ounces) are shown below. Construct a 95 percent confidence interval for the population standard deviation. Note: Scale was only accurate to the nearest ¼ ounce. (Data are from a project by statistics student Ju
