Problem 4:

LO2 4. Six samples of five observations each have been taken of 80 kg concrete slabs produced by a machine, and the results are displayed below. a. Using factors from Table 10-3, determine the upper and lower control limits for sample mean and range, and decide if the process is in control. b. A new sample results in the following slab weights: 81.0, 81.0, 80.8, 80.6, and 80.5. Use the control limits deter- mined in part a to decide if the process is still in control. Sample 1 2 3 4 5 6 79.2 80.5 79.6 78.9 80.5 79.7 78.8 78.7 79.4 79.4 79.6 80.6 80.0 81.0 80.4 79.7 80.4 80.5 78.4 80.4 80.3 79.4 80.8 80.0 81.0 80.1 80.8 80.6 78.8 8