The time in minutes to replace vehicle wiper blades at a service center was monitored using a mean and a range chart. Six samples of n = 20 observations were obtained and the sample means and ranges were computed:

Sample Mean Range Sample Mean Range 1 3.06 .42 4 3.13 .46 2 3.15 .50 5 3.06 .46 3 3.11 .41 6 3.09 .45

a. Using the factors in Table 10.3, determine upper and lower limits for mean and range charts.

Is the process within the control limits?

b. The time in minutes needed to assemble security cameras at a production facility was recorded for eight samples of 15 observations each, and means and ranges were computed. Using factors from Table 10.3, compute control limits for the means and ranges to determine if the process is in control.

Sample Mean Range Sample Mean Range 1 7.10 .52 5 7.21 .46 2 6.92 .48 6 8.01 .55 3 7.25 .50 7 7.80 .53 4 7.54 .51 8 7.63 .49

 LO.1