Chapter 13.6, Problem 13.50ACI

Quality of rewritable CDs. A Japanese compact disc (CD) manufacturer has a daily production rate of about 20.000 CD-RW (rewritable disks). Quality is monitored by randomly sampling 200 finished CDs every other hour from the production process and testing them for defects. If one or more defects are discovered, the CD is considered de­fective and is destroyed. The production process operates 20 hours per day, 7 days a week. The table below reports data for the last 3 days of production.

Day	Hour	Number of Defectives
1	1	13
	2	5
	3	2
	4	3
	5	2
	6	3
	7	1
	8	2
	9	1
	10	1
2	1	11
	2	6
	3	2
	4	3
	5	1
	6	3
	7	1
	8	2
	9	3
	10	1
3	1	9
	2	5
	3	2
	4	1
	5	3
	6	2
	7	4
	8	2
	9	1
	10	1

1. a. Construct a p-chart for the CD-RW production process.
2. b. What does it indicate about the stability of the process? Explain.
3. c. What advice can you give the manufacturer to assist them in their search for the special cause(s) of variation that is plaguing the process?