9. An assembly line consisting of three consecutive workstations produces two radio models:

DiGi-l and DiGi-2. The following table provides the assembly times for the three workstations.

Minutes per unit Workstation 1

2 3

DiGi-l 6

5 4

DiGi-2 4

4 6

The daily maintenance for workstations 1,2, and 3 consumes 10%,14%, and 12%, respectively, of the maximum 480 minutes available for each workstation each day.

(a) The company wishes to determine the optimal product mix that will minimize the idle (or unused) times in the three workstations. Determine the optimum utilization of the workstations. [Hint; Express the sum of the idle times (slacks) for the three operations in terms of the original variables.]

(b) Determine the worth of decreasing the daily maintenance time for each workstation by 1 percentage point.

(c) It is proposed that the operation time for all three workstations be increased to 600 minutes per day at the additional cost of $1.50 per minute. Can this proposal be improved?