Wilson Foods has an 800 phone number that customers can call if they have questions about cooking a Wilson recipe. On average, there are 225 customers calls per hour and an average phone call lasts 1.5 minutes. Wilson pays each customer representative (CR) $16 per hour in wages and benefits. The telephone company charges Wilson $0.18 for each minute a customer is on hold or speaking to a CR. The goodwill cost is $0.20 for each minute a customer is on hold and $0.05 for each minute a customer speaking to a CR.

6-a) To minimize the hourly cost of operating the hot line service, how many CRs should Wilson use?

6-b) To ensure that the average waiting time for a customer is no greater than 1 minute, how many CRs should Wilson use?

6-c) To ensure that the average queue length (or the average number of calls on hold) is at most 1, how many CRs should Wilson use?

6-d) To ensure that the probability that a customer does not have to wait is at least 95%, how many CRs should Wilson use?