More on updating control chart limits. In given Exercise, control limits for the weight of ground beef were obtained using historical results. Using given Table, estimate the process μ and process σ. Do either of these values suggest a change in the process center and spread?

Exercise
Control limits for a meat-packaging process. A meat-packaging company produces 1-pound packages of ground beef by having a machine slice a long circular cylinder of ground beef crosswise as it passes through the machine. The timing between consecutive cuts will alter the weight of each section. Table gives the weight of three consecutive sections of ground beef taken each hour over two 10-hour days. Past experience indicates that the process mean is 1.028 and the weight varies with σ = 0.024 lb.

(a) Calculate the center line and control limits for an x‾ chart.

(b) What are the center line and control limits for an s chart for this process?

(c) Create the x‾ and s charts for these 20 consecutive samples.

(d) Does the process appear to be in control? Explain.