Q&A Hero

Q: Independent random samples taken on two university campuses revealed the following information concerning the average amount of money spent on textbooks during the fall semester.University AUniversity BSample Size5040Average Purchase$260$250Population Standard Deviation()$20$23We want to determine if, on the average, students at University A spent more on textbooks then the students at University B.a. Compute the test statistic.b. Compute the p-value.c. What is your conclusion? Let = .05.

Q: The business manager of a local health clinic is interested in estimating the difference between the fees for extended office visits in her center and the fees of a newly opened group practice. She gathered the following information regarding the two offices.Health ClinicGroup PracticeSample Size50 visits45 visitsSample Mean$21$19Population Standard Deviation$2.75$3.00Develop a 95% confidence interval estimate for the difference between the average fees of the two offices.

Q: Consider the following results for two samples randomly taken from two normal populations with equal variances.Sample ISample IISample Size2835Sample Mean4844Population Standard Deviation910a. Develop a 95% confidence interval for the difference between the two population means.b. Is there conclusive evidence that one population has a larger mean?Explain.

Q: Maxforce, Inc. manufactures racquetball racquets by two different manufacturing processes (A and B). Because the management of this company is interested in estimating the difference between the average time it takes each process to produce a racquet, they select independent samples from each process. The results of the samples are shown below.Process AProcess BSample Size3235Sample Mean (in minutes)4347Population Variance (2)6470a. Develop a 95% confidence interval estimate for the difference between the average times of the two processes.b. Is there conclusive evidence to prove that one process takes longer than the other? If yes, which process? Explain.

Q: The following sample information is given concerning the ACT scores of high school seniors form two local schools. School A School B = 14 = 15 = 25 = 23 = 16 = 10 Develop a 95% confidence interval estimate for the difference between the two populations.

Q: Refer to Exhibit 10-16. The null hypothesisa. should be rejectedb. should not be rejectedc. was designed incorrectlyd. None of these alternatives is correct.

Q: Refer to Exhibit 10-16. The null hypothesis is to be tested at the 5% level of significance. The p-value is a. less than .01 b. between .01 and .025 c. between .025 and .05 d. between .05 and .10

Q: Refer to Exhibit 10-16. The test statistic to test the null hypothesis equals a. 0.22 b. 0.84 c. 4.22 d. 4.5

Q: Refer to Exhibit 10-16. The mean square within treatments (MSE) equals a. 400 b. 500 c. 1,687.5 d. 2,250

Q: Exhibit 10-16SSTR = 6,750 H0: 1 = 2 = 3 = 4SSE = 8,000 Ha: at least one mean is differentnT= 20Refer to Exhibit 10-16. The mean square between treatments (MSTR) equalsa. 400b. 500c. 1,687.5d. 2,250

Q: Refer to Exhibit 10-15. The conclusion of the test is that the meansa. are equalb. may be equalc. are not equald. None of these alternatives is correct.

Q: Refer to Exhibit 10-15. If at 95% confidence, we want to determine whether or not the means of the populations are equal, the p-value is a. between 0.01 and 0.025 b. between 0.025 and 0.05 c. between 0.05 and 0.1 d. greater than 0.1

Q: Refer to Exhibit 10-15. The computed test statistics is a. 32 b. 8 c. 0.667 d. 4

Q: Refer to Exhibit 10-15. The mean square between treatments (MSTR) is a. 36 b. 16 c. 8 d. 32

Q: Refer to Exhibit 10-15. The number of degrees of freedom corresponding to within treatments is a. 12 b. 2 c. 3 d. 15

Q: Exhibit 10-15The following is part of an ANOVA table that was obtained from data regarding three treatments and a total of 15 observations.Source of VariationDFSSBetween Treatments64Error (Within Treatments)96Refer to Exhibit 10-15. The number of degrees of freedom corresponding to between treatments isa. 12b. 2c. 3d. 4

Q: Refer to Exhibit 10-14. The conclusion of the test is that the meansa. are equalb. may be equalc. are not equald. None of these alternatives is correct.

Q: Refer to Exhibit 10-14. If at 95% confidence we want to determine whether or not the means of the populations are equal, the p-value is a. greater than 0.1 b. between 0.05 and 0.1 c. between 0.025 and 0.05 d. less than 0.01

Q: Refer to Exhibit 10-14. The mean square between treatments (MSTR) is a. 36 b. 16 c. 64 d. 15

Q: Refer to Exhibit 10-14. The number of degrees of freedom corresponding to within treatments is a. 22 b. 4 c. 5 d. 18

Q: Exhibit 10-14Part of an ANOVA table is shown below.ANOVASource of VariationDFSSMSFBetween Treatments648Within Treatments (Error)2Total100Refer to Exhibit 10-14. The number of degrees of freedom corresponding to between treatments isa. 18b. 2c. 4d. 3

Q: Refer to Exhibit 10-13. If at 95% confidence, we want to determine whether or not the means of the populations are equal, the p-value isa. between 0.01 and 0.025b. between 0.025 and 0.05c. between 0.05 and 0.1d. greater than 0.1

Q: Refer to Exhibit 10-13. The test statistic is a. 2.25 b. 6 c. 2.67 d. 3

Q: Refer to Exhibit 10-13. The mean square within treatments (MSE) is a. 60 b. 15 c. 300 d. 20

Q: Exhibit 10-13Part of an ANOVA table is shown below.ANOVASource of VariationDFSSMSFBetween Treatments3180Within Treatments (Error)Total18480Refer to Exhibit 10-13. The mean square between treatments (MSTR) isa. 20b. 60c. 300d. 15

Q: Refer to Exhibit 10-12. If at 95% confidence we want to determine whether or not the means of the five populations are equal, the p-value isa. between 0.05 and 0.10b. between 0.025 and 0.05c. between 0.01 and 0.025d. less than 0.01

Q: Refer to Exhibit 10-12. The test statistic is a. 0.2 b. 5.0 c. 3.75 d. 15

Q: Refer to Exhibit 10-12. The mean square within treatments (MSE) is a. 50 b. 10 c. 200 d. 600

Q: Refer to Exhibit 10-12. The mean square between treatments (MSTR) is a. 3.34 b. 10.00 c. 50.00 d. 12.00

Q: Refer to Exhibit 10-12. The number of degrees of freedom corresponding to within treatments is a. 60 b. 59 c. 5 d. 4

Q: Refer to Exhibit 10-12. The number of degrees of freedom corresponding to between treatments is a. 60 b. 59 c. 5 d. 4

Q: Exhibit 10-12In a completely randomized experimental design involving five treatments, 13 observations were recorded for each of the five treatments (a total of 65 observations). The following information is provided.SSTR = 200 (Sum Square Between Treatments)SST = 800 (Total Sum Square)Refer to Exhibit 10-12. The sum of squares within treatments (SSE) isa. 1,000b. 600c. 200d. 1,600

Q: Refer to Exhibit 10-11. The null hypothesisa. should be rejectedb. should not be rejectedc. should be revisedd. None of these alternatives is correct.

Q: Refer to Exhibit 10-11. The null hypothesis is to be tested at the 1% level of significance. The p-value is a. greater than 0.1 b. between 0.1 and 0.05 c. between 0.05 and 0.025 d. between 0.025 and 0.01

Q: Refer to Exhibit 10-11. The test statistic to test the null hypothesis equals a. 0.944 b. 1.059 c. 3.13 d. 19.231

Q: Refer to Exhibit 10-11. The mean square within treatments (MSE) equals a. 1.872 b. 5.86 c. 34 d. 36

Q: Refer to Exhibit 10-11. The mean square between treatments (MSTR) equals a. 1.872 b. 5.86 c. 34 d. 36

Q: Exhibit 10-11To test whether or not there is a difference between treatments A, B, and C, a sample of 12 observations has been randomly assigned to the 3 treatments. You are given the results below.TreatmentObservationA20302533B22262028C40302822Refer to Exhibit 10-11. The null hypothesis for this ANOVA problem isa. 1=2b. 1=2=3c. 1=2=3=4d. 1=2= ... =12

Q: Refer to Exhibit 10-10. At 95% confidence, what is the conclusion for this study?a. There is a significant difference in the time spent in the store between men and women.b. There is no significant difference in the time spent in the store between men and women.c. It is impossible to make a decision on the basis of the information given.d. The sample sizes must be equal in order to answer this question.

Q: Refer to Exhibit 10-10. The test statistic for the difference between the two population means is a. 1.96 b. 27.96 c. 21.00 d. 26.00

Q: Refer to Exhibit 10-10. The 95% confidence interval for the difference between the two population means is a. 24.04 to 27.96 b. 1.96 c. -1.96 to 1.96 d. -24.04 to 27.96

Q: Refer to Exhibit 10-10. The point estimate for the standard deviation of the difference between the means of the two populations is a. 9 b. -1 c. -9 d. 1

Q: Exhibit 10-10A local department store is studying the shopping habits of its customers. They think that the longer customers spend in the store the more they buy. Their study resulted in the following information regarding the amount of time women and men spent in a store.WomenMenMean6 minutes 12 seconds5 minutes 46 secondsPopulation Standard deviation4 seconds5 secondsSample size3250Refer to Exhibit 10-10. The point estimate for the difference between the means of the two populations isa. 1 minute 26 secondsb. 34 secondsc. 26 secondsd. 13 seconds

Q: Refer to Exhibit 10-9. At 90% confidence the null hypothesisa. should not be rejectedb. should be rejectedc. should be revisedd. None of these alternatives is correct.

Q: Refer to Exhibit 10-9. The test statistic isa. 1.645b. 1.96c. 2.096d. 2.256

Q: Exhibit 10-9Two major automobile manufacturers have produced compact cars with the same size engines. We are interested in determining whether or not there is a significant difference in the MPG (miles per gallon) of the two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The following data show the results of the test.DriverManufacturer AManufacturer B1322822722326274262452524629257312882527Refer to Exhibit 10-9. The mean for the differences isa. 0.50b. 1.5c. 2.0d. 2.5

Q: Refer to Exhibit 10-8. The null hypothesisa. should be rejectedb. should not be rejectedc. should be revisedd. None of these alternatives is correct.

Q: Refer to Exhibit 10-8. The p-value is a. 0.0013 b. 0.0026 c. 0.0042 d. 0.0084

Q: Refer to Exhibit 10-8. The test statistic is a. 0.098 b. 1.645 c. 2.75 d. 3.01

Q: Exhibit 10-8In order to determine whether or not there is a significant difference between the hourly wages of two companies, the following data have been accumulated.Company ACompany BSample size8060Sample mean$16.75$16.25Population standard deviation$1.00$0.95Refer to Exhibit 10-8. A point estimate for the difference between the two sample means isa. 20b. 0.50c. 0.25d. 1.00

Q: Refer to Exhibit 10-7. A 95% interval estimate for the difference between the two population means isa. 0.078 to 1.922b. 1.922 to 2.078c. 1.09 to 4.078d. 1.078 to 2.922

Q: Exhibit 10-7In order to estimate the difference between the average hourly wages of employees of two branches of a department store, the following data have been gathered.Downtown StoreNorth Mall StoreSample size2520Sample mean$15$14Sample standard deviation$2$1For this problem, the degrees of freedom are computed to be 36.Refer to Exhibit 10-7. A point estimate for the difference between the two sample means isa. 1b. 2c. 3d. 4

Q: Refer to Exhibit 10-6. A 95% confidence interval estimate for the difference between the average purchases of the customers using the two different credit cards isa. 49 to 64b. 11.68 to 18.32c. 125 to 140d. 8 to 10

Q: Refer to Exhibit 10-6. At 95% confidence, the margin of error is a. 1.694 b. 3.32 c. 1.96 d. 15

Q: Exhibit 10-6The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card. You are given the following information.Store's CardMajor Credit CardSample size6449Sample mean$140$125Population standard deviation$10$8Refer to Exhibit 10-6. A point estimate for the difference between the mean purchases of the users of the two credit cards isa. 2b. 18c. 265d. 15

Q: Refer to Exhibit 10-5. If the null hypothesis is tested at the 5% level, the null hypothesisa. should be rejectedb. should not be rejectedc. should be revisedd. None of these alternatives is correct.

Q: Refer to Exhibit 10-5. The null hypothesis tested is H0: md= 0. The test statistic for the difference between the two population means is a. 2 b. 0 c. -1 d. -2

Q: Refer to Exhibit 10-5. The 95% confidence interval for the difference between the two population means is a. -3.776 to 1.776 b. -2.776 to 2.776 c. -1.776 to 2.776 d. 0 to 3.776

Q: Exhibit 10-5The following information was obtained from matched samples.IndividualMethod 1Method 2175259368477556Refer to Exhibit 10-5. The point estimate for the difference between the means of the two populations (method 1 " method 2) isa. -1b. 0c. -4d. 2

Q: The board of directors of a corporation has agreed to allow the human resources manager to move to the next step in planning day care service for employees' children if the manager can prove that at least 25% of the employees have interest in using the service. The HR manager polls 300 employees and 90 say they would seriously consider utilizing the service. At the = .10 level of significance, is there enough interest in the service to move to the next planning step?

Q: Fast "˜n Clean operates 12 laundromats on the east side of the city. All of Fast "˜n Clean's clothes dryers have a label stating "20 minutes for $1.00." You question the accuracy of the dryers' clocks and decide to conduct an observational study. You randomly select 36 dryers in several different Fast "˜n Clean locations, put $1.00 in each and time the drying cycle. The sample mean drying time is 20 minutes and 25 seconds. The manufacturer of the dryer states that the standard deviation for 20-minute drying cycles is 1 minute.a. Using the sample data and = .05, test the validity of the label on the dryers. Apply the p-value and critical value approaches to conducting the two-tail hypothesis test.b. Conduct the same two-tail hypothesis test, but this time use the confidence interval approach to hypothesis testing.

Q: At a certain manufacturing plant, a machine produces ball bearings that should have a diameter of 0.500 mm. If the machine produces ball bearings that are either too small or too large, the ball bearings must be scrapped. Every hour, a quality control manager takes a random sample of 36 ball bearings to test to see if the process is "out of control" (i.e. to test to see if the average diameter differs from 0.500 mm). Assume that the process is maintaining the desired standard deviation of .06 mm. The results from the latest sample follow:4680.5210.4210.4760.4480.3460.4520.5130.4650.3950.5580.5260.3540.4740.4470.4050.4110.4530.4560.4770.5290.4400.5700.3190.4710.4800.4990.4460.4050.5570.4680.5210.4210.4760.4480.346At a .01 level of significance, use Excel to test whether the process is "out of control."

Q: The sponsors of televisions shows targeted at the market of 5 " 8 year olds want to test the hypothesis that children watch television at most 20 hours per week. The population of viewing hours per week is known to be normally distributed with a standard deviation of 6 hours. A market research firm conducted a random sample of 30 children in this age group. The resulting data follows:529.717.510.419.418.414.610.112.518.219.130.922.219.811.819.027.725.327.426.516.121.720.632.927.015.617.119.220.117.7At a .10 level of significance, use Excel to test the sponsors' hypothesis.

Q: Which Excel function would notbe appropriate to use when conducting a hypothesis test for a population proportion?a. NORMSDISTb. COUNTIFc. STDEVd. All are appropriate.

Q: Refer to Exhibit 9-6. At a .05 level of significance, it can be concluded that the proportion of the population in favor of candidate A is a. significantly greater than 75% b. not significantly greater than 75% c. significantly greater than 80% d. not significantly greater than 80%

Q: Refer to Exhibit 9-6. The p-value is a. 0.2112 b. 0.05 c. 0.025 d. 0.0156

Q: Exhibit 9-6A random sample of 100 people was taken. Eighty of the people in the sample favored Candidate A. We are interested in determining whether or not the proportion of the population in favor of Candidate A is significantly more than 75%.Refer to Exhibit 9-6. The test statistic isa. 0.80b. 0.05c. 1.25d. 2.00

Q: The academic planner of a university thinks that at least 35% of the entire student body attends summer school. The correct set of hypotheses to test his belief isa. H0: p> 0.35 Ha: p0.35b. H0: p0.35 Ha: p> 0.35c. H0: p0.35 Ha: p< 0.35d. H0: p> 0.35 Ha: p0.35

Q: In the past, 75% of the tourists who visited Chattanooga went to see Rock City. The management of Rock City recently undertook an extensive promotional campaign. They are interested in determining whether the promotional campaign actually increasedthe proportion of tourists visiting Rock City. The correct set of hypotheses isa. H0: p> 0.75 Ha: p0.75b. H0: p< 0.75 Ha: p0.75c. H0: p0.75 Ha: p< 0.75d. H0: p0.75 Ha: p> 0.75

Q: The school's newspaper reported that the proportion of students majoring in business is at least 30%. You plan on taking a sample to test the newspaper's claim. The correct set of hypotheses is a. H0: p< 0.30 Ha: p0.30 b. H0: p0.30 Ha: p> 0.30 c. H0: p0.30 Ha: p< 0.30 d. H0: p> 0.30 Ha: p0.30

Q: Excel's __________ function can be used to calculate a p-value for a hypothesis test when is unknown. a. RAND b. TDIST c. NORMSDIST d. Not enough information is given to answer this question.

Q: Refer to Exhibit 9-5. If the test is done at a 2% level of significance, the null hypothesis should a. not be rejected b. be rejected c. Not enough information is given to answer this question. d. None of the other answers are correct.

Q: Refer to Exhibit 9-5. The p-value is equal to a. -0.0166 b. 0.0166 c. 0.0332 d. 0.9834

Q: Exhibit 9-5n = 16H0: 80= 75.607Ha: < 80 = 8.246Assume population is normally distributed.Refer to Exhibit 9-5. The test statistic equalsa. -2.131b. -0.53c. 0.53d. 2.131

Q: Refer to Exhibit 9-4. At a .05 level of significance, it can be concluded that the mean age isa. not significantly different from 24b. significantly different from 24c. significantly less than 24d. significantly less than 25

Q: Exhibit 9-4A random sample of 16 students selected from the student body of a large university had an average age of 25 years. We want to determine if the average age of all the students at the university is significantly different from 24. Assume the distribution of the population of ages is normal with a standard deviation of 2 years.Refer to Exhibit 9-4. The test statistic isa. 1.96b. 2.00c. 1.645d. 0.05

Q: Read the tstatistic from the table of tdistributions and circle the correct answer. A one-tailed test (lower tail), a sample size of 10 at a .10 level of significance; t=a. 1.383b. -1.372c. -1.383d. -2.821

Q: Read the tstatistic from the table of tdistributions and circle the correct answer. A one-tailed test (upper tail), a sample size of 18 at a .05 level of significance t= a. 2.12 b. 1.734 c. -1.740 d. 1.740

Q: Read the tstatistic from the table of tdistributions and circle the correct answer. A two-tailed test, a sample of 20 at a .20 level of significance; t = a. 1.328 b. 2.539 c. 1.325 d. 2.528

Q: For a sample size of 30, changing from using the standard normal distribution to using the tdistribution in a hypothesis test, a. will result in the rejection region being smaller b. will result in the rejection region being larger c. would have no effect on the rejection region d. Not enough information is given to answer this question.