Consider the diameter data in Exercise 15-75. Assume that the desired process target is 10.0 millimeters.

(a) Estimate the process standard deviation.

(b) Construct an EWMA control chart with λ = 0.2. Does the process appear to be in control?

(c) Construct an EWMA control chart with λ = 0.5. Compare your results to part (a).

Exercise 15-75

An automatic senson measures the diameter of holes in consecutive order. The results of measuring 25 holes follow.

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Sample Diameter Sample Diameter 1 9.94 14 9.99 9.93 15 10.12 3 10.09 16 9.81 9.98 9.73 17 5 10.11 18 10.14 6. 9.99 19 9.96 10.11 20 10.06 8. 9.84 21 10.11 9. 9.82 22 9.95 10 10.38 23 9.92 11 9.99 24 10.09 12 10.41 25 9.85 13 10.36