(a) Develop another plan for the Mexican roofing manufacturer described in Examples 1 to 4 (pages 550-553) and Solved Problem 13.1 (pages 564-565). For this plan, plan 5, the firm wants to maintain a constant workforce of six, using subcontracting to meet remaining demand. Is this plan preferable?

(b) The same roofing manufacturer in examples 1 to 4 and Solved Problem 13.1 has yet a sixth plan. A constant workforce of seven is selected, with the remainder of demand filled by subcontracting.