The data below represent precision length measurements of 80 consecutive structural frame members coming off the assembly line. Sample# x1 x2 Sample# x1 x4 1 74.33 74.34 74.35 74.4074.37 74.37 74.41 74.37 2 74.39 74.38 74.41 7437 74.40 74.37 74.39 74.33 3 74.35 74.39 74.43 74417442 74.37 74.35 74.41 74.37 74.40 74.32 7437 74.36 74.38 74.40 74.42 5 74.40 74.35 74.39 74.36 74.36 74.30 74.34 74.39 74.34 74.34 74.38 74.34 74.34 74.36 \"m \"m a) Create a? and R charts from the given data. b) Is this process in control? c) Revise the J? and R charts so that only in-control points are used. Are all points still in control under the new control limits? Iterate this process if necessary to obtain acceptable control charts