A quality control study was undertaken by the supervisor of a group of computer programmers. For each of the last 20 days, 25 program modules were randomly selected and inspected for coding errors. The numbers of errors observed per day are recorded in the table.

a. Plot the number of coding errors per day in a c-chart.

b. Locate the center line for the c-chart.

c. Locate upper and lower control limits for the c-chart. Is the process in control?

d. Conduct a runs analysis for the c-chart. What does this imply?

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CODING Day 1 2 3 4 5 6. 7. 8 9 10 Coding Errors 7 3 9 8 2 5 10 5 7 6. Day 11 12 13 14 15 16 17 18 19 20 Coding Errors 1 4 11 8 6 6 9 2 12 9