The data in the following table were collected for the purpose of constructing an x@chart.

a. Calculate x and R for each sample.

b. Calculate x and R.

c. Calculate and plot the centerline and the upper and lower control limits for the x@chart.

d. Calculate and plot the A, B, and C zone boundaries of the x@chart.

e. Plot the 20 sample means on the x@chart. Is the process in control? Justify your answer. Sample Measurements 1 19.4 19.7 20.6 21.2 2 18.7 18.4 21.2 20.7 3 20.2 18.8 22.6 20.1 4 19.6 21.2 18.7 19.4 5 20.4 20.9 22.3 18.6 6 17.3 22.3 20.3 19.7 7 21.8 17.6 22.8 23.1 8 20.9 17.4 19.5 20.7 9 18.1 18.3 20.6 20.4 10 22.6 21.4 18.5 19.7 11 22.7 21.2 21.5 19.5 12 20.1 20.621.020.21319.718.6 21.2 19.1 14 18.6 21.7 17.7 18.3 15 18.2 20.419.819.2 1618.920.7 23.220.01720.519.721.4 17.8 18 21.0 18.719.921.2 19 20.5 19.6 19.8 21.8 20 20.6 16.9 22.4 19.7