Twenty samples of subgroup size 2 (n = 2) were collected for a variable measurement. Determine the upper control limit (UCL) for an R-chart if the mean of the sample ranges equals 4.4. Factors for calculating control limits n A2 D3 D4 2 1.880 0 3.267 3 1.023 0 2.574 4 0.729 0 2.282 5 0.577 0 2.114 6 0.483 0 2.004