2 : 15-16 Colonel Electric is a large company that produces lightbulbs and other electrical products. One particu- lar lightbulb is supposed to have an average life of about 1,000 hours before it burns out. Periodically, the company will test five of these and measure the average time before these burn out. The following table gives the results of 10 such samples: SAMPLE 1 2 3 4 5 6 7 8 9 10 Mean 979 1,087 1,080 934 1,072 1,007 952 986 1,063 958 Range 50 94 57 65 135 134 101 98 145 84 (a) What is the overall average of these means? What is the average range? (b) What are the upper and lower control limits for a 99.7% control chart for the mean? (c) Does this process appear to be in control? Explain. DISCUSSION QUESTIONS AND PROBLEMS 545 @. 15-17 For Problem 15-16, develop upper and lower control limits for the range. Do these samples indicate that the process is in control? 2: 15-18 Kate Drew has been hand-painting wooden Christ- mas ornaments for several years. Recently, she has hired some friends to help her increase the volume of her business. In checking the quality of the work, she notices that some slight blemishes occasionally are apparent. A sample of 20 pieces of work resulted in the following number of blemishes on each piece: 0, 2, 1, 0, 0, 3, 2, 0, 4, 1, 2, 0, 0, 1, 2, 1, 0, 0, 0, 1. De- velop upper and lower control limits for the number of blemishes on each piece. 2: 15-19 A new president at Big State University has made student satisfaction with the enrollment and registra- tion process one of her highest priorities. Students must see an advisor, sign up for classes, obtain a parking permit, pay tuition and fees, and buy text- books and other supplies. During one registration period, 10 students every hour are sampled and asked about satisfaction with each of these areas. Twelve different groups of students were sampled, and the number in each group who had at least one complaint is as follows: 0, 2, 1, 0, 0, 1, 3, 0, 1, 2, 2, 0. Develop upper and lower control limits (99.7%) for the proportion of students with complaints. A.barcamurity is an area of increasing concern. The