The commercial loan operation of a financial institution has a standard for processing new loan applications in 24 hours. Table 7E.2 shows the number of applications processed each day for the last 20 days and the number of applications that required more than 24 hours to complete.

(a) Set up the fraction nonconforming control chart for this process. Use the variable-width control limit approach. Plot the preliminary data in table 7E.2 on the chart. Is the process in statistical control?
(b) Assume that assignable causes can be found for any out-of-control points on this chart. What center line should be used for process monitoring in the next period, and how should the control limits be calculated?

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TABLE 7E.2 Loan Application Data for Exercise 7.5 Number of Number Number of Number Day Applications Late Day Applications Late 1200 12 13 14 2 15 16 17 18 19 219 238 250 302 219 246 251 273 245 10 240 300 200 5 20 246 258 275 274 9 120260 10