Bath concentrations are measured hourly in a chemical process. Data (in ppm) for the last 32 hours are shown in Table 9E.4 (read down from left). The process target is µ0 = 175 ppm.

(a) Estimate the process standard deviation.
(b) Construct a tabular CUSUM for this process, using standardized values h= 5 and k = ½. Interpret this chart.

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TABLE 9E.4 Bath Concentration 160 186 190 206 158 195 189 210 150 179 185 1216 151 184 182 212 153 175 1S 211 154 192 180 202 158 186 183 205 162 197 186 197