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All Textbook Solutions for Introduction to Business Statistics

9.12E 9.13E 9.14E 9.15E 9.16E 9.17E 9.18E 9.19E 9.20E 9.21E 9.22E 9.23E 9.24E 9.25E 9.26E 9.27E 9.28E 9.29E 9.30E 9.31E 9.32E 9.33E 9.34E 9.35E 9.36E 9.37E 9.38E 9.39E 9.40E 9.41E 9.42E 9.43E An airline has surveyed a simple random sample of air travelers to find out whether they would be interested in paying a higher fare in order to have access to e-mail during their flight. Of the 400 travelers surveyed, 80 said e-mail access would be worth a slight extra cost. Construct a 95% confidence interval for the population proportion of air travelers who are in favor of the airline’s e-mail idea.9.45E 9.46E 9.47E 9.48E 9.49E 9.50E 9.51E 9.52E 9.53E 9.54E Estelle McCarthy, a candidate for state office in New Jersey, has been advised that she must get at least 65% of the union vote in her state. A recent political poll of likely voters included 800 union-member respondents, and 60% of them said they intended to vote for Ms. McCarthy. Based on the survey, construct and interpret the 95% confidence interval for the population proportion of likely-voter union members who intend to vote for Ms. McCarthy. Is the 65% level of support within the confidence interval?Given your answer to the preceding question, commenton the possibility that Ms. McCarthy might not succeed in obtaining the level of union support she needs.9.56E 9.57E 9.58E 9.59E 9.60E 9.61E 9.62E 9.63E 9.64E 9.65E 9.66E 9.67E 9.68E 9.69E 9.70E 9.71E 9.72E 9.73E 9.74E 9.75E 9.76E 9.77E 9.78E 9.79E 10.90CE 10.91CE 10.92CE 10.93CE 10.94CE 10.95CE 10.96CE 10.97CE 10.98CE 10.99CE 10.100CE 10.101CE 10.102CE 10.103CE 10.104CE 10.105CE 10.106CE 10.107CE 10.108CE 10.109CE 10.110CE 10.111CE 10.112CE 10.113CE 2.1IC 2.2IC 12.1AE 12.2AE 12.3AE 13.1AE 13.2AE 13.3AE 13.4AE 10.1E 10.2E 10.3E The president of a company that manufactures central home air conditioning units has told an investigative reporter that at least 85% of its homeowner customers claim to be “completely satisfied” with the overall purchase experience. If the reporter were to subject the president’s statement to statistical scrutiny by questioning a sample of the company’s residential customers, would the test be one-tail or two-tail? What would be the appropriate null and alternative hypotheses?10.5E 10.6E Following a major earthquake, the city engineer must determine whether the stadium is structurally sound for an upcoming athletic event. If the null hypothesis is “the stadium is structurally sound,” and the alternative hypothesis is “the stadium is not structurally sound,”which type of error (Type I or Type II) would the engineer least like to commit?10.8E 10.9E 10.10E 10.11E 10.12E 10.13E 10.14E 10.15E 10.16E 10.17E 10.18E 10.19E 10.20E 10.21E 10.22E 10.23E 10.24E 10.25E 10.26E 10.27E 10.28E 10.29E In the past, patrons of a cinema complex have spent an average of $5.00 for popcorn and other snacks, with a standard deviation of $1.80. The amounts of these expenditures have been normally distributed. Following an intensive publicity campaign by a local medical society, the mean expenditure for a sample of 18 patrons is found to be $4.20. In a one-tail test at the 0.05 level of significance, does this recent experience suggest a decline in spending? Determine and interpret the p-value for the test.Following maintenance and calibration, an extrusion machine produces aluminum tubing with a mean outside diameter of 2.500 inches, with a standard deviation of 0.027 inches. As the machine functions over an extended number of work shifts, the standard deviation remains unchanged, but the combination of accumulated deposits and mechanical wear causes the mean diameter to “drift” away from the desired 2.500 inches. For a recent random sample of 34 tubes, the mean diameter was 2.509 inches. At the 0.01 level of significance, does the machine appear to be in need of maintenance and calibration? Determine and interpret the p-value for the test.A manufacturer of electronic kits has found that the mean time required for novices to assemble its new circuit tester is 3 hours, with a standard deviation of 0.20 hours. A consultant has developed a new instructional booklet intended to reduce the time an inexperienced kit builder will need to assemble the device. In a test of the effectiveness of the new booklet, 15 novices require a mean of 2.90 hours to complete the job. Assuming the population of times is normally distributed, and using the 0.05 level of significance, should we conclude that the new booklet is effective? Determine and interpret the p-value for the test. ( DATA SET ) Note: Exercises 10.33 and 10.34 require a computer and statistical software.10.33E A machine that fills shipping containers with driveway filler mix is set to deliver a mean fill weight of 70.0 pounds. The standard deviation of fill weights delivered by the machine is known to be 1.0 pounds. For a recent sample of 35 containers, the fill weights are listed in data file XR10034. Using the mean for this sample, and assuming that the population standard deviation has remained unchanged at 1.0 pounds, examine whether the mean fill weight delivered by the machine might now be something other than 70.0 pounds. Identify and interpret the p-value for the test. Using the 0.05 level of significance, what conclusion will be reached?10.35E 10.36E 10.37E 10.38E 10.39E 10.40E 10.41E The average age of passenger cars in use in the United States is 9.0 years. For a simple random sample of 34 vehicles observed in the employee parking area of a large manufacturing plant, the average age is 10.4 years, with a standard deviation of 3.1 years. At the 0.01 level of significance, can we conclude that the average age of cars driven to work by the plant’s employees is greater than the national average? Source: polk.com, August 9, 2006.10.43E 10.44E 10.45E 10.46E 10.47E During 2008, college work-study students earned a mean of $1478. Assume that a sample consisting of 45 of the work-study students at a large university was found to have earned a mean of $1503 during that year, with a standard deviation of $210. Would a one-tail test at the 0.05 level suggest the average earnings of this university’s work-study students were significantly higher than the national mean? Source: Bureau of the Census, StatisticalAbstract of the United States 2009, p. 178.10.49E 10.50E 10.51E In response to an inquiry from its national office, the manager of a local bank has stated that her bank’s average service time for a drive-through customer is93 seconds. A student intern working at the bank happens to be taking a statistics course and is curious as to whether the true average might be some value other than 93 seconds. The intern observes a simple random sample of 50 drive-through customers whose average service time is 89.5 seconds, with a standard deviation of 11.3 seconds. From these sample results, and using the 0.05 level of significance, what conclusion would the student reach with regard to the bank manager’s claim?10.53E 10.54E 10.55E 10.56E 10.57E 10.58E 10.59E 10.60E 10.61E 10.62E 10.63E 10.64E 10.65E 10.66E 10.67E 10.68E 10.69E 10.70E 10.71E 10.72E 10.73E 10.74E 10.75E 10.76E 10.77E 10.78E 10.79E 10.80E 10.81E 10.82E 10.83E 10.84E 10.85E 10.86E 10.87E 10.88E 10.89E 11.75CE 11.76CE 11.77CE 11.78CE 11.79CE 11.80CE 11.81CE 11.82CE 11.83CE 11.84CE 11.85CE 11.86CE 11.87CE 11.88CE 11.89CE 11.90CE 11.91CE 11.92CE 11.93CE 11.94CE 11.95CE 11.96CE 11.97CE 11.98CE 11.99CE 11.100CE 11.101CE 1.1IC 1.2IC 1.3IC 2.1IC 2.2IC 2.3IC 2.4IC 1BC 2BC 3BC 14.1AE 14.2AE 14.3AE 14.4AE 14.5AE 14.6AE 11.1E 11.2E Using independent random samples, a researcher is comparing the number of hours of television viewed last week for high school seniors versus sophomores. The results are shown here. Assuming normal populationswith equal standard deviations, does it appear that the average number of television hours per week could be equal for these two populations? What is the most accurate statement that could be made about the p-value for the test? Seniors: x1=3.9hourss1=1.2hoursn1=32 Sophomores: x2=3.5hourss2=1.4hoursn2=30 11.4E 11.5E 11.6E 11.7E 11.8E 11.9E 11.10E 11.11E 11.12E 11.13E 11.14E 11.15E 11.16E 11.17E 11.18E 11.19E 11.20E 11.21E A tire company is considering switching to a new type of adhesive designed to improve tire reliability in high-temperature and overload conditions. In laboratory “torture” tests with temperatures and loads 90% higher than the maximum normally encountered in the field, 15 tires constructed with the new adhesive run an average of 65 miles before failure, with a standard deviation of 14 miles. For 18 tires constructed with the conventional adhesive, the mean mileage before failure was 53 miles, with a standard deviation of 22 miles. Assuming normal populations and using the 0.05 level of significance, can we conclude that the new adhesive is superior to the old under such test conditions? What is the most accurate statement that could be made about the p-value for this test?11.23E 11.24E 11.25E 11.26E 11.27E 11.28E 11.29E 11.30E 11.31E 11.32E 11.33E 11.34E 11.35E 11.36E 11.37E 11.38E 11.39E 11.40E 11.41E 11.42E 11.43E 11.44E 11.45E 11.46E 11.47E 11.48E The students in an aerobics class have been weighed both before and after the 5-week class, with the following results: Using the 0.05 level of significance, evaluate the effectiveness of the program. Using the appropriate statistical table, what is the most accurate statement we can make about the p-value for this test?11.50E 11.51E 11.52E 11.53E 11.54E 11.55E 11.56E 11.57E 11.58E 11.59E 11.60E 11.61E 11.62E 11.63E 11.65E 11.66E 11.67E 11.68E

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