I need help solving part B, please.

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 3.13 .46 2 3.15 .50 5 3.06 .46 3 3.11 .41 3.09 .45 .42 4 6 Click here for the Excel Data File Factors for three-sigma control limits for and R charts Factor for I Chart, A2 Number of Observations in Subgroup n 2 3 4 5 6 7 FACTORS FOR R CHARTS Lower Upper Control Control Limit, Limit, D3 D4 0 3.27 0 2.57 0 2.28 0 2.11 0 2.00 0.08 1.92 0.14 1.86 0.18 1.82 0.22 1.78 0.26 1.74 0.28 1.72 0.31 1.69 0.33 1.67 0.35 1.65 0.36 1.64 0.38 1.62 0.39 1.61 0.40 1.60 0.41 1.59 1.88 1.02 0.73 0.58 0.48 0.42 0.37 0.34 0.31 0.29 0.27 0.25 0.24 0.22 0.21 0.20 0.19 0.19 0.18 9 10 11 12 13 14 15 16 18 19 20 a. Using the factors in the above table, determine upper and lower limits for mean and range charts. (Do not round intermediate calculations. Round your mean value to 3 decimal places and range value to 4 decimal places.) 3.181 3.019 Upper limit for mean Lower limit for mean Upper limit for range Lower limit for range 0.7155 0.1845 a1. Is the process in control? The process is in control. The process is not in control. 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 the above table, compute control limits for the means and ranges. (Round your answers to 3 decimal places.) Sample 1 2 Mean 7.10 6.92 7.25 7.54 Range .52 .48 .50 .51 Sample 5 6 7 Mean 7.21 8.01 7.80 7.63 Range .46 .55 .53 .49 3 4 8 7.433 7.433 Upper limit for mean Lower limit for mean Upper limit for range Lower limit for range 7.433 7.433