Samples of n=4 items are taken from a process at regular intervals. A normally distributed quality characteristic is measured and x and s values are calculated for each sample. After 50 subgroups have been analyzed, we have i=150xi=1,000andi=150si=72 (a) Compute the control limit for the x and s control charts. (b) Assume that all points on both charts plot within the control limits. What are the natural tolerance limits of the process? (c) If the specification limits are 194.0, what are your conclusions regarding the ability of the process to produce items conforming to specifications