a$)$ Construct control charts for the sample means and ranges showing the control limits and

comment on the results.

$(10$ marks$)$

b$)$ The specification asks for a tolerance of $74$ inch $\frac{+}{-}\mathrm{.}04$ inch. Calculate the process capability

indices $C_p$ and $C_{pl}$ and comment on these. What level of process capability should you strive to

achieve for $C_p$ and $C_{pk}.$

$(10$ marks$)$