A process is in statistical control with x = 199 and R = 3.5. The control chart uses a sample size of n= 4. Specifications are at 200 ± 8. The quality characteristic is normally distributed.

USL = 200 + 8 = 208; LSL = 200 €“ 8 = 192
(a) Estimate the potential capability of the process.
(b) Estimate the actual process capability.
(c) How much improvement could be made in process performance if the mean could be centered at the nominal value?

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n=4; μ=x =199; R=3.5; σ.-R/d,-3.5/2.059 = 1.70