Colonel Electric is a large company that produces lightbulbs

Colonel Electric is a large company that produces lightbulbs and other electrical products. One particular lightbulb is supposed to have an average life of 1,000 hours before it burns out. Periodically the company will test 5 of these and measure the average time before these burn out. The following table gives results of 10 such samples:

a) What is the overall average of the sample means?

b) What is the average range?

c) What are the upper and lower control limits for a 99% control chart for the mean?

d) Does process appear to be in control? Explain your answer.

Sample1 2 34 56 7 9 10 Mean979 1087 1080 934 1072 1007952 986 1063 958 Range50945765 1351341019814584

Solution