# Question: Control charts for x and R are maintained on the

Control charts for x and R are maintained on the tensile strength of a metal fastener. After 30 samples of size n= 6 are analyzed, we find that

(a) Compute control limits on the R chart.

(b) Assuming that the R chart exhibits control, estimate the parameters µ and σ.

(c) If the process output is normally distributed, and if the specifications are 440 + – 40, can the process meet the specifications? Estimate the fraction nonconforming.

(d) If the variance remains constant, where should the mean be located to minimize the fraction nonconforming?

(a) Compute control limits on the R chart.

(b) Assuming that the R chart exhibits control, estimate the parameters µ and σ.

(c) If the process output is normally distributed, and if the specifications are 440 + – 40, can the process meet the specifications? Estimate the fraction nonconforming.

(d) If the variance remains constant, where should the mean be located to minimize the fraction nonconforming?

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