10.9. A sample of five units is taken from a process every half hour. It is known that the process standard deviation is in control with s = 2.0. The values for the last 20 samples are shown in Table 10E.7.

- TABLE 10E.7 Data for Exercise 10.9 \begin{tabular}{cccc} SampleNumber & x & SampleNumber & x \\ \hline 1 & 41.5 & 11 & 40.6 \\ 2 & 42.7 & 12 & 39.4 \\ 3 & 40.5 & 13 & 38.6 \\ 4 & 39.8 & 14 & 42.5 \\ 5 & 41.6 & 15 & 41.8 \\ 6 & 44.7 & 16 & 40.7 \\ 7 & 39.6 & 17 & 42.8 \\ 8 & 40.2 & 18 & 43.4 \\ 9 & 41.4 & 19 & 42.0 \\ 10 & 43.9 & 20 & 41.9 \\ \hline \end{tabular} - TABLE 10E.7 Data for Exercise 10.9 \begin{tabular}{cccc} SampleNumber & x & SampleNumber & x \\ \hline 1 & 41.5 & 11 & 40.6 \\ 2 & 42.7 & 12 & 39.4 \\ 3 & 40.5 & 13 & 38.6 \\ 4 & 39.8 & 14 & 42.5 \\ 5 & 41.6 & 15 & 41.8 \\ 6 & 44.7 & 16 & 40.7 \\ 7 & 39.6 & 17 & 42.8 \\ 8 & 40.2 & 18 & 43.4 \\ 9 & 41.4 & 19 & 42.0 \\ 10 & 43.9 & 20 & 41.9 \\ \hline \end{tabular}