a$)$ What type of control chart would you use to monitor this process

and why?

b$)$ What are the $3-$sigma control limits for this process? Assume

that the historical complaint rate is unknown.

c$)$ Is the process mean in control, according to the control limits$?$

Why or why not?

d$)$ Assume now that the historical complaint rate has been $4$ calls a

week. What would the $3-$sigma control limits for this process be

now? Is the process in control according to the control limits$?$