SS 7.34. A paper mill uses a control chart to monitor the imperfection in finished rolls of paper. Production output is inspected for 20 days, and the resulting data are shown in Table 7E.9. Use these data to set up a control chart for nonconformities per roll of paper. Does the process appear to be in sta- tistical control? What center line and control lim- its would you recommend for controlling current production? Table 7E.9 Data on Imperfections in Rolls of Paper Total Number Total Number of Number of Rolls Number of Imper- of Rolls Day Produced Imper- fections Day Produced fections 18 12 11 18 18 2 18 14 12 18 14 3 24 20 13 18 9 4 22 18 14 20 10 22 15 15 20 14 22 12 16 20 13 20 11 17 24 16 8 20 15 18 24 18 9 20 12 19 22 20 10 20 10 20 21 17