- Crash Davis is the line supervisor for the Benicia, California, plant of a manufacturer of inline skates. Close fit is important for in-line skating gear, so Crash tests each day's production by selecting a size 13 pairs from the line and skating to get his afternoon cappuccino down the street. Crash points out that he selects each pair "at random." Is this, in fact, a random sample of the day's production, or is it judgmental? - Wayne Nesbitt is an inspector from the Shell Motorcycle Helmet Company. Wayne makes his inspections by selecting a random helmet from the recently produced flux (production line). If the size of the helmet is close enough to the size of Wayne's hat, he tries it to verify if it has any defects that could deteriorate its adjustment and/or comfort. If the helmet is too small or big, he returns it to the helmet production line. Is this sampling method random or is it judgmental? - Burt Purdue, manager of the Sea Island Development Company, wants to find out residents' feelings toward the development's recreation facilities and the improvements they would like to see implemented. The development includes residents of various ages and income levels, but a large proportion are middle-class residents between the ages of 30 and 50. As yet, Burt is unsure whether there are differences among age groups or income levels in their desire for recreation facilities. Would stratified random sampling be appropriate here?

- Joan Fargo, president of Fargo-Lanna Ltd., wants to offer videotaped courses for employees during the lunch hour, and wants to get some idea of the courses that employees would like to see offered. Accordingly, she has devised a ballot that an employee can fill out in 5 minutes, listing his or her preferences among the possible courses. The ballots, which cost very little to print, will be distributed with paychecks, and the results will be tabulated by the staff. Ms. Fargo plans to poll all employees. Are there any reasons to poll a sample of the employees rather than the entire population?

- HAL Corporation manufactures large computer systems and has always prided itself on the reliability of its System 666 central processing units. In fact, past experience has shown that the monthly downtime of System 666 CPUs averages 41 minutes and has a standard deviation of 8 minutes. The computer center at a large state university maintains an installation built around six System 666 CPUs. James Kitchen, the director of the computer center, feels that a satisfactory level of service is provided to the university community if the average downtime of the six CPUs is less than 50 minutes per month. In any given month, what is the probability that Kitchen will be satisfied with the level of service? - Calvin Ensor, president of General Telephone Corp., is upset at the number of telephones produced by GTC that have faulty receivers. On average, 110 telephones per day are being returned because of this problem, and the standard deviation is 64. Mr. Ensor has decided that unless he can be at least 80 percent certain that, on average, no more than 120 phones per day will be returned during the next 48 days, he will order a repair and redesign of the process. Will the repair and redesign be ordered?