Question: A 2005 study found that 202 women

> The Fischer Theatre compared attendance at its Saturday and Sunday matinee performances of a major Broadway musical. At α = .05, is the Sunday matinee attendance significantly greater than the Saturday matinee? Date Sunday Saturday Oct

> Streeling University surveyed a random sample of employees to estimate the frequency of sexually inappropriate comments they had heard at work during the last month. 32 of 80 respondents said they had heard such comments. The survey was repeated after al

> A retailer compared the frequency of customer merchandise returns at two locations. Last month, store A had 57 returns on 760 purchases, while store B had 62 returns on 1,240 purchases. At α = .01, was the return rate significantly higher at store A?

> Students in nutrition classes at two high schools were asked to keep track of the number of times during the past month that they ordered from a fast-food chain restaurant. Sonando High School ………………………………………… Gedacht High School / = 14.51 ………………………………

> Male and female students in a finance class were asked how much their last tank of gas cost. Can you conclude that on average males spent more on gas than females? Males ………………………………………………………… Females / = $43.20 ………………………………….………… / = $36.60 s1 = $8.30

> Do positive emotions reduce susceptibility to colds? Healthy volunteers were divided into two groups based on their emotional profiles and each group was exposed to rhinovirus (the common cold). Of those who reported mostly positive emotions, 14 of 50 de

> Below are data on truck production (number of vehicles completed) during the second shift at five truck plants for each day in a randomly chosen week. Research question: Are the mean production rates the same by plant and by day? Trucks Produced dur

> Advertisers fear that users of DVD recorders will “fast forward” past commercials when they watch a recorded program. A leading British pay television company told their advertisers that this effect might be offset because DVD users watch more TV. A samp

> One group of accounting students used simulation programs, while another group received a tutorial. Scores on an exam were compared. (a). Construct a 90 percent confidence interval for the true difference in mean scores, explaining any assumptions tha

> Three samples of each of three types of PVC pipe of equal wall thickness are tested to failure under three temperature conditions, yielding the results shown below. Research questions: Is mean burst strength affected by temperature and/or by pipe type? I

> On a random basis, Bob buys a small take-out coffee from one of two restaurants. As a statistics project in the month of May, he measured the temperature of each cup immediately after purchase, using an analog cooking thermometer. Assuming equal variance

> As a volunteer for a consumer research group, LaShonda was assigned to analyze the freshness of three brands of tortilla chips. She examined four randomly chosen bags of chips for four brands of chips from three different stores. She recorded the number

> Is there a difference between the variance in ages for full-time seasonal employees and part-time seasonal employees at Vail Resorts? A sample of 62 full-time employees had an s12 = 265.69. A sample of 78 part-time employees had an s22 = 190.44. (a). T

> Rates of return (annualized) in two investment portfolios are compared over the last 12 quarters. They are considered similar in safety, but portfolio B is advertised as being “less volatile.” (a). At Î&plusmn

> A cognitive retraining clinic assists outpatient victims of head injury, anoxia, or other conditions that result in cognitive impairment. Each incoming patient is evaluated to establish an appropriate treatment program and estimated length of stay. To se

> Two labs produce 1280 3 1024 LCD displays. At random, records are examined for 12 independently chosen hours of production in each lab, and the number of bad pixels per thousand displays is recorded. (a). Assuming equal variances, at the .01 level of

> Nine homes are chosen at random from real estate listings in two suburban neighborhoods, and the square footage of each home is noted in the following table. At the .10 level of significance, is there a difference between the average sizes of homes in th

> A certain company will purchase the house of any employee who is transferred out of state and will handle all details of reselling the house. The purchase price is based on two assessments, one assessor being chosen by the employee and one by the company

> Concerned about graffiti, mayors of nine suburban communities instituted a citizen Community Watch program. (a). State the hypotheses to see whether the number of graffiti incidents declined. (b). Find the test statistic. (c). State the critical valu

> Emergency room arrivals in a large hospital showed the statistics below for 2 months. At α = .05, has the variance changed? Show all steps clearly, including an illustration of the decision rule. Statistic October November Mean arrival

> A ski company in Vail owns two ski shops, one on the west side and one on the east side of Vail. Ski hat sales data (in dollars) for a random sample of 5 Saturdays during the 2004 season showed the following results. Is there a significant difference in

> Researchers analyzed 12 samples of two kinds of Stella’s decaffeinated coffee. The caffeine in a cup of decaffeinated espresso had a mean of 9.4 mg with a standard deviation of 3.2 mg, while brewed decaffeinated coffee had a mean of 12.7 mg with a standa

> A ski company in Vail owns two ski shops, one on the west side and one on the east side of Vail. Is there a difference in daily average goggle sales between the two stores? Assume equal variances. (a). State the hypotheses for a two-tailed test. (b).

> In MiniCase 10.2, we found that the mean methane gas emissions for the two pneumatic controller manufacturers were not equal. When choosing formula 10.3 to calculate the t statistic, we assumed that their variances were not equal. Was this a valid assump

> Cash withdrawals from a college credit union for a random sample of 30 Fridays and 30 Mondays are shown. At α = .01, is there a difference in the mean withdrawal on Monday and Friday? (a). Make stacked dot plots of the data (a sketch is

> The average take-out order size for Ashoka Curry House restaurant is shown. Assuming equal variances, at α = .05, is there a significant difference in the order sizes? (a). State the hypotheses. (b). State the decision rule and sketch i

> Do male and female school superintendents earn the same pay? Salaries for 20 males and 17 females in a certain metropolitan area are shown below. At α 5= .01, were the mean superintendent salaries greater for men than for women? (a). Sta

> One group of accounting students took a distance learning class, while another group took the same course in a traditional classroom. At α = .10, is there a significant difference in the mean scores listed below? (a). State the hypothese

> In a 15-day survey of air pollution in two European capitals, the mean particulate count (micrograms per cubic meter) in Athens was 39.5 with a standard deviation of 3.75, while in London the mean was 31.5 with a standard deviation of 2.25. (a). Assumi

> Based on the sample data below, is the average Medicare spending in the northern region significantly less than the average spending in the southern region at the 1 percent level? (a). State the hypotheses and decision rule. (b). Find the test statis

> An experimental bumper was designed to reduce damage in low-speed collisions. This bump er was installed on an experimental group of vans in a large fleet, but not on a control group. At the end of a trial period, accident data showed 12 repair incidents

> From her firm’s computer telephone log, an executive found that the mean length of 64 telephone calls during July was 4.48 minutes with a standard deviation of 5.87 minutes. She vowed to make an effort to reduce the length of calls. The August phone log

> Are women’s feet getting bigger? Retailers in the last 20 years have had to increase their stock of larger sizes. Wal-Mart Stores, Inc., and Payless Shoe Source, Inc., have been aggressive in stocking larger sizes, and Nordstromâ&

> Has the cost to outsource a standard employee background check changed? A random sample of 10 companies in spring 2010 showed a sample average of $105 with a sample standard deviation equal to $32. A random sample of 10 different companies in spring 2012

> In 2009 Noodles & Company introduced spaghetti and meatballs to their menu. Before putting it on the menu, they performed taste tests to determine the best-tasting spaghetti sauce. In a paired comparison, 70 tasters were asked to rate their satisfaction

> Former U.S. Vice President Dick Cheney received a lot of publicity after his fourth heart attack. A portable defibrillator was surgically implanted in his chest to deliver an electric shock to restore his heart rhythm whenever another attack was threaten

> In San Francisco, a sample of 3,200 wireless routers showed that 1,312 used encryption (to prevent hackers from intercepting information). In Seattle, a sample of 1,800 wireless routers showed that 684 used encryption. (a). Set up hypotheses to test wh

> In a marketing class, 44 student members of virtual (Internet) project teams (group 1) and 42 members of face-to-face project teams (group 2) were asked to respond on a 1–5 scale to the question: “As compared to other teams, the members helped each other

> A study revealed that the 30-day readmission rate was 31.5 percent for 400 patients who received after-hospital care instructions (e.g., how to take their medications) compared to a readmission rate of 38.5 percent for 400 patients who did not receive su

> Does a “follow-up reminder” increase the renewal rate on a magazine subscription? A magazine sent out 760 subscription renewal notices (without a reminder) and got 703 renewals. As an experiment, they sent out 240 subscription renewal notices (with a rem

> Vail Resorts tracks the proportion of seasonal employees who are rehired each season. Rehiring a seasonal employee is beneficial in many ways, including lowering the costs incurred during the hiring process such as training costs. A random sample of 833

> At a University of Colorado woman’s home basketball game, a random sample of 25 concession purchases showed a mean of $7.12 with a standard deviation of $2.14. For the next week’s home game, the admission ticket had a discount coupon for popcorn printed

> A ski company in Vail owns two ski shops, one on the east side and one on the west side. Sales data showed that at the eastern location there were 56 pairs of large gloves sold out of 304 total pairs sold. At the western location there were 145 pairs of

> When the background music tempo was slow, the mean amount of bar purchases for a sample of 17 restaurant patrons was $30.47 with a standard deviation of $15.10. When the background music tempo was fast, the mean amount of bar purchases for a sample of 14

> After John F. Kennedy Jr. was killed in an airplane crash at night, a survey was taken, asking whether a noninstrument-rated pilot should be allowed to fly at night. Of 409 New York State residents, 61 said yes. Of 70 aviation experts who were asked the

> eShopNet, an online clothing retailer, is testing a new e-mail campaign by sending one version of the e-mail with the word “free” in the subject line (version A) to a group of 1500 customers and another version of the e-mail with the word “discount” in t

> How many full-page advertisements are found in a magazine? In an October issue of Muscle and Fitness, there were 252 ads, of which 97 were full-page. For the same month, the magazine Glamour had 342 ads, of which 167 were full-page. (a). Is the differe

> To test his hypothesis that students who finish an exam first get better grades, a professor kept track of the order in which papers were handed in. Of the first 25 papers, 10 received a B or better compared with 8 of the last 24 papers handed in. Is the

> A study of the Fortune 100 board of director members showed that there were 36 minority women holding board seats out of 202 total female board members. There were 142 minority men holding board seats out of 993 total male board members. (a). Treating

> Are college students more likely than young children to eat cereal? Researchers surveyed both age groups to find the answer. The results are shown in the table below. (a). State the hypotheses used to answer the question. (b). Using α =

> In an early home game, an NBA team made 66 of their 94 free throw attempts. In one of their last home games, the team made 68 of 89 attempts. (a). At α = .10, did the team significantly improve its free throw percentage (left-tailed test)? (b). Use Ex

> The top food snacks consumed by adults aged 18–54 are gum, chocolate candy, fresh fruit, potato chips, breath mints/candy, ice cream, nuts, cookies, bars, yogurt, and crackers. Out of a random sample of 25 men, 15 ranked fresh fruit in their top five sna

> In a bumper test, three test vehicles of each of three types of autos were crashed into a barrier at 5 mph, and the resulting damage was estimated. Crashes were from three angles: head-on, slanted, and rear-end. The results are shown below. Research ques

> The average mpg usage for a 2009 Toyota Prius for a sample of 10 tanks of gas was 45.5 with a standard deviation of 1.8. For a 2009 Honda Insight, the average mpg usage for a sample of 10 tanks of gas was 42.0 with a standard deviation of 2.3. (a). Assu

> Is a state’s income related to its high school dropout rate? Research question: Do the high school dropout rates differ among the five income quintiles? State High School Dropout Rates by Income Groups Lowest Income Quintile 2nd In

> The Environmental Protection Agency (EPA) advocates a maximum arsenic level in water of 10 micrograms per liter. Below are results of EPA tests on randomly chosen wells in a suburban Michigan county. Research question: Is the mean arsenic level affected

> An ANOVA study was conducted to compare dental offices in five small towns. The response variable was the number of days each dental office was open last year. Research question: Is there a difference in the means among these five towns? Dental Clin

> An MBA director examined GMAT scores for the first 10 MBA applicants (assumed to be a random sample of early applicants) for four academic quarters. Research question: Do the mean GMAT scores for early applicants differ by quarter? GMAT Scores of Fi

> Below are results of braking tests of the Ford Explorer on glare ice, packed snow, and split traction (one set of wheels on ice, the other on dry pavement), using three braking methods. Research question: Is the mean stopping distance affected by braking

> The results shown below are mean productivity measurements (average number of assemblies completed per hour) for a random sample of workers at each of three plants. Research question: Are the mean hourly productivity levels the same for workers in these

> The waiting time (in minutes) for emergency room patients with non-life-threatening injuries was measured at four hospitals for all patients who arrived between 6:00 and 6:30 p.m. on a certain Wednesday. The results are shown below. Research question: Ar

> In a bumper test, three types of autos were deliberately crashed into a barrier at 5 mph, and the resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with the results shown below. Research question: Are the mean cra

> Mean output of solar cells of three types are measured six times under random light intensity over a period of 5 minutes, yielding the results shown. Research question: Is the mean solar cell output the same for all cell types? Solar Cell Output (wa

> The XYZ Corporation is interested in possible differences in days worked by salaried employees in three departments in the financial area. A survey of 23 randomly chosen employees reveals the data shown below. Because of the casual sampling methodology i

> Is there a difference in the average number of years’ seniority between returning part-time seasonal employees and returning full-time seasonal employees at a Vail Resorts’ ski mountain? From a random sample of 191 returning part-time employees, the aver

> Below are grade point averages for 25 randomly chosen university business students during a recent semester. Research question: Are the mean grade point averages the same for students in these four class levels? Grade Point Averages of 25 Business S

> Is the water on your airline flight safe to drink? It is not feasible to analyze the water on every flight, so sampling is necessary. The Environmental Protection Agency (EPA) found bacterial contamination in water samples from the lavatories and galley

> A 20-minute consumer survey mailed to 500 adults aged 25234 included a $5 Starbucks gift certificate. The same survey was mailed to 500 adults aged 25234 without the gift certificate. There were 65 responses from the first group and 45 from the second gr

> A survey of 100 mayonnaise purchasers showed that 65 were loyal to one brand. For 100 bath soap purchasers, only 53 were loyal to one brand. Perform a two-tailed test comparing the proportion of brand-loyal customers at α = .05.

> In 2006, a sample of 200 in-store shoppers showed that 42 paid by debit card. In 2009, a sample of the same size showed that 62 paid by debit card. (a) Formulate appropriate hypotheses to test whether the percentage of debit card shoppers increased. (b

> During the period 199021998 there were 46 Atlantic hurricanes, of which 19 struck the United States. During the period 199922006 there were 70 hurricanes, of which 45 struck the United States. (a) State the hypotheses to test whether the percentage of h

> Find the test statistic and do the two-sample test for equality of proportions. a. Repeat buyers at two car dealerships: p1 = .30, n1 = 50, p2 = .54, n2 = 50, α = .01, left-tailed test. b. Honor roll students in two sororities: p1 = .45, n1 = 80, p2 = .

> Find the sample proportions and test statistic for equal proportions. Find the p-value. a. Dissatisfied workers in two companies: x1 = 40, n1 = 100, x2 = 30, n2 = 100, α = .05, two tailed test. b. Rooms rented at least a week in advance at two hotels: x

> Calculate the test statistic and p-value for a test of equal population proportions. What is your conclusion? a. Left-tailed test, α = .10, x1 = 28, n1 = 336, x2 = 14, n2 = 112 b. Right-tailed test, α = .05, x1 = 276, n1 = 300, x2 = 440, n2 = 500 c. Two

> Calculate the test statistic and p-value for a test of equal population proportions. What is your conclusion? a. Right-tailed test, α = .10, x1 = 228, n1 = 240, x2 = 703, n2 = 760 b. Left-tailed test, α = .05, x1 = 36, n1 = 80, x2 = 66, n2 = 120 c. Two-

> Repeat the previous exercise, assuming unequal variances. Calculate the p-value using Excel, and show the Excel formula you used. Previous exercise: Do a two-sample test for equality of means assuming equal variances. Calculate the p-value. a. Compari

> A newly installed automatic gate system was being tested to see if the number of failures in 1,000 entry attempts was the same as the number of failures in 1,000 exit attempts. A random sample of eight delivery trucks was selected for data collection. Do

> Below is a random sample of shoe sizes for 12 mothers and their daughters. (a) At α = .01, does this sample show that women’s shoe sizes have increased? State your hypotheses and show all steps clearly. (b) Is the deci

> The coach told the high school swim team that times in the 200-yard individual medley in the Division I-AA Swim Championships typically are more than 1/2 second faster than their seed times going into the meet. At α = .05, do these times (i

> The U.S. government’s “Cash for Clunkers” program encouraged individuals to trade in their old gas-guzzlers for new, more efficient vehicles. At α = .05, do the data below support the hy

> Blue Box is testing a new “half price on Tuesday” policy on DVD rentals at a sample of 10 locations. (a). At α = .10, do the data show that the mean number of Tuesday rentals has increased? (b). Is th

> In preliminary tests of a vaccine that may help smokers quit by reducing the “rush” from tobacco, 64 subjects who wanted to quit smoking were given either a placebo or the vaccine. Of the 32 in the placebo group, only 3 quit smoking for 30 days (the U.S.

> A 20-minute consumer survey mailed to 500 adults aged 25–34 included a $5 Starbucks gift certificate. The same survey was mailed to 500 adults aged 25–34 without the gift certificate. There were 65 responses from the first group and 45 from the second gr

> A survey of 100 mayonnaise purchasers showed that 65 were loyal to one brand. For 100 bath soap purchasers, only 53 were loyal to one brand. Form a 95 percent confidence interval for the difference of proportions. Does it include zero?

> This table shows partial results for a one-factor ANOVA, (a). Calculate the F test statistic. (b). Calculate the p-value using Excel’s function 5F.DIST.RT (F,DF1,DF2). (c). Find the critical value F.05 from Appendix F or using Excel

> A manufacturing process drills holes in sheet metal that are supposed to be .5000 cm in diameter. Before and after a new drill press is installed, the hole diameter is carefully measured (in cm) for 12 randomly chosen parts. At α = .05, do

> An experimental surgical procedure is being studied as an alternative to the old method. Both methods are considered safe. Five surgeons perform the operation on two patients matched by age, sex, and other relevant factors, with the results shown. The ti

> The American Bankers Association reported that, in a sample of 120 consumer purchases in France, 60 were made with cash, compared with 26 in a sample of 50 consumer purchases in the United States. Construct a 90 percent confidence interval for the differ

> Consider a one-factor ANOVA with n1 = 6, n2 = 5, n3 = 4, n4 = 6, n5 = 4. (a). How many possible comparisons of means are there? (b). State the degrees of freedom for Tukey’s T. (c). Find the critical value of Tukey’s T for α = .05.

> Consider a one-factor ANOVA with n1 = 9, n2 = 10, n3 = 7, n4 = 8. (a). How many possible comparisons of means are there? (b). State the degrees of freedom for Tukey’s T. (c). Find the critical value of Tukey’s T for α = .05.

> For each data set: (a) State the hypotheses. (b) Use Excel’s Data Analysis (or MegaStat or MINITAB) to perform the one-factor ANOVA, using α = .05. (c) State your conclusion about the population means. (d) Interpret th

> For each data set: (a) State the hypotheses. (b) Use Excel’s Data Analysis (or MegaStat or MINITAB) to perform the one-factor ANOVA, using α = .05. (c) State your conclusion about the population means. (d) Interpret th

> For each data set: (a) State the hypotheses. (b) Use Excel’s Data Analysis (or MegaStat or MINITAB) to perform the one-factor ANOVA, using α = .05. (c) State your conclusion about the population means. (d) Interpret th

> For each data set: (a) State the hypotheses. (b) Use Excel’s Data Analysis (or MegaStat or MINITAB) to perform the one-factor ANOVA, using α = .05. (c) State your conclusion about the population means. (d) Interpret th

> In a one-factor ANOVA with sample sizes n1 = 8, n2 = 5, n3 = 6, n4 = 6, the test statistic was Fcalc = 3.251. (a). State the hypotheses. (b). State the degrees of freedom for the test. (c). What is the critical value of F for α = .05? (d). What is y

> In a one-factor ANOVA with sample sizes n1 = 5, n2 = 7, n3 = 6, n4 = 7, n5 = 5, the test statistic was Fcalc = 2.447. (a). State the hypotheses. (b). State the degrees of freedom for the test. (c). What is the critical value of F for α = .10? (d). W

> Oxnard Petro, Ltd. has three suppliers of catalysts. Orders are placed with each supplier every 15 working days, or about once every 3 weeks. The delivery time (days) is recorded for each order over 1 year. Are the main effects significant? Is there an i

> (a) At α = .05, does the following sample show that daughters are taller than their mothers? (b) Is the decision close? (c) Why might daughters tend to be taller than their mothers? Why might they not? Daughter's Height (cm) Mother's

> A market research firm is testing consumer reaction to a new shampoo on four age groups in four regions. There are five consumers in each test panel. Each consumer completes a 10-question product satisfaction instrument with a 5-point scale (5 is the hig

> Oxnard Petro, Ltd., has three interdisciplinary project development teams that function on an ongoing basis. Team members rotate from time to time. Every 4 months (three times a year) each department head rates the performance of each project team (using