=+12-hour shift one day. Historical data shows the proportion of defects to be 6.21%. Either use technology to accommodate the different sample sizes, or use 250 as an approximation for all of them.

Hour No. of Defects Sample Size 1 13 241 2 18 265 3 17 256 4 14 249 5 20 221 6 19 276 7 12 244 8 15 261 9 12 259 10 17 243 11 14 237 12 16 257 13 18 252 14 19 260 15 17 245 16 20 255 17 19 262 18 14 244 19 22 270 20 18 254 Assuming the process was previously in control,

a) Calculate the center line.