A normally distributed quality characteristic is monitored through use of an and anRchart. These charts have the following parameters (n=4):
Chart
RChart
UCL = 626.0
UCL = 18.795
Center line = 620.0
Center line = 8.236
LCL = 614.0
LCL = 0
Both charts exhibit control.
(a) What is the estimated standard deviation of the process?
(b) Suppose anschart were to be substituted for theRchart. What would be the appropriate parameters of theschart?
(c) If specifications on the product were 610 ??15, what would be your estimate of the process fraction nonconforming?
(d) What could be done to reduce this fraction nonconforming?
(e) What is the probability of detecting a shift in the process mean to 610 on the first sample following the shift (σ remains constant)?
(f) What is the probability of detecting the shift in part (e) by at least the third sample after the shift occurs?
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