1. Your hospital is negotiating with medical insurance providers, who would like to reduce the amount they pay as reimbursement for hospital stays. For a particular procedure, they would like to reduce payment by $300 and have patients go home one day earlier. To see what effect this would have on hospital costs, a random sample of 50 patients who were recently admitted for this procedure was analyzed. Had they left one day earlier, the average savings would have been $322.44, and the standard deviation was found to be $21.71. Construct a 95% confidence interval for the mean savings, per patient, for the larger population of recent patients.
2. The Glen Valley Steel Company manufactures steel bars. If the production process is working properly, it turns out steel bars with lengths that are normally distributed with a mean of at least 2.8 feet, with a standard deviation of 0.20 foot (as determined by the engineering specifications on the production equipment involved). Longer steel bars can be used or altered, but shorter steel bars must be scrapped. You select a sample of 25 bars, and the mean length is 2.73 feet. Do you need to adjust the production equipment? (use a significance level of 0.05).
3. Meier and Frank is a chain of department stores located in the Northwest. The company has issued its own credit cards for a number of years. As a new employee in the finance department, imagine that you have been assigned to a major investigation of the firm’s credit policies designed to reduce bad debt losses. You are requested to investigate the relationship between marital status at the time the card is issued and the subsequent payment record of the individual. You randomly select 100 credit cards issued three years previously. Of the 70 individuals that were married at the time the cards were issued, 11 have defaulted on a payment. Of the 30 individuals who were single when the cards were issued, 7 have defaulted. Do these data present sufficient evidence to indicate that marital status affects credit-worthiness? Use Alpha = 0.05.
4. The National Restaurant Association is interested in determining if there is a relationship between the type of pizza pie which Americans prefer and the region of the country in which they live. The association randomly selects 285 Americans and records the category of pizza pie which best describes their preference and the region of the country in which they live. The results are as follows:
Type of Pizza Pie Preferred: North - 40, South - 30, East - 35, West - 45
Type of Pizza Pie Preferred: Thick Crust - 17, South - 15, East - 21, West - 22
Type of Pizza Pie Preferred: Pan Pizza - 15, South - 15, East - 15, West - 15
At α = .10, what can the Association conclude?
5. Fancy Fish, a fine dining upscale restaurant in Northridge, California and 2016 Open Table Diners’ Choice award winner, is enjoying its eighteenth season of providing delectable food, exceptional service, and beautiful outdoor dining experiences. “Saturday - Half-off Bottled Wine Night” has made Fancy Fish one of the San Fernando Valley’s favorite restaurants. Every Saturday night, guests can enjoy half-off every bottle of wine on the wine list while dining in the restaurant or on the terrace. The owner began offering “Saturday - Half-off Bottled Wine Night” in 2010 as an incentive for guests to dine at Fancy Fish when the economy was in a recession. Now that the economy is booming, the owner is considering whether the promotion should be continued, or even expanded. One concern is the effect that the promotion is having on the overall revenue generated from sales to the participants. A random sample of 28 checks was collected over the course of one month of Saturday nights. Fourteen checks were from customers participating in the half-off promotion, and the other 14 checks were from customers not participating. The total revenue from each check (less alcohol, tax, and tip) is presented below. Do these data present sufficient evidence that the checks of participants is significantly different from checks of non-participants? What is your recommendation to the owner regarding the status of the promotion?
With Wine Discount: 35, 46, 35, 44, 36, 29, 36, 29, 48, 29, 29, 60, 36, 64
W/O Wine Discount: 43, 47, 24, 47, 13, 49, 36, 53, 50, 51, 22, 44, 32, 36
6. A major distillery for alcoholic beverages is interested in gaining a large share of the market composed of people aged 18-23 (in those states where 18 is the legal drinking age). Beer and wine are the traditional favorites of this age group. However, Bill Schuessler, the firm’s marketing manager, and Carol Pringle, manager of research and development, feel that a new version of distilled apple cider will appeal to this younger market. While they are sure that the alcohol content should remain below 5 percent, they are not sure exactly what it should be. Therefore, five versions of the cider have been prepared and each version has been tasted by a random sample of 25 young consumers. Each consumer has evaluated the drink on a 100-point scale, with the higher scores representing a greater liking for the product. The results of the test appear below. What should Schuessler and Pringle conclude?
Version: 1% - 16, 2% - 40, 3% - 81, 4% - 89, 5% - 53
Version: 1% - 18, 2% - 62, 3% - 81, 4% - 95, 5% - 20
Version: 1% - 72, 2% - 11, 3% - 35, 4% - 10, 5% - 98
Version: 1% - 57, 2% - 49, 3% - 16, 4% - 70, 5% - 67
Version: 1% - 30, 2% - 40, 3% - 83, 4% - 94, 5% - 92
Version: 1% - 16, 2% - 63, 3% - 35, 4% - 06, 5% - 08
Version: 1% - 96, 2% - 77, 3% - 20, 4% - 20, 5% - 59
Version: 1% - 39, 2% - 93, 3% - 64, 4% - 20, 5% - 49
Version: 1% - 31, 2% - 62, 3% - 76, 4% - 38, 5% - 03
Version: 1% - 78, 2% - 91, 3% - 19, 4% - 47, 5% - 32
Version: 1% - 03, 2% - 93, 3% - 33, 4% - 30, 5% - 47
Version: 1% - 74, 2% - 42, 3% - 33, 4% - 28, 5% - 72
Version: 1% - 09, 2% - 06, 3% - 09, 4% - 90, 5% - 95
Version: 1% - 42, 2% - 23, 3% - 12, 4% - 42, 5% - 25
Version: 1% - 16, 2% - 15, 3% - 08, 4% - 02, 5% - 04
Version: 1% - 21, 2% - 45, 3% - 40, 4% - 74, 5% - 20
Version: 1% - 21, 2% - 58, 3% - 57, 4% - 80, 5% - 50
Version: 1% - 56, 2% - 61, 3% - 78, 4% - 95, 5% - 97
Version: 1% - 45, 2% - 65, 3% - 66, 4% - 99, 5% - 24
Version: 1% - 91, 2% - 34, 3% - 84, 4% - 98, 5% - 49
Version: 1% - 91, 2% - 22, 3% - 21, 4% - 20, 5% - 35