Hart Manufacturing makes three products. Each product requires manufacturing operations in three departments: A, B, and C. The labor-hour requirements, by department, are as follows:

Department Product 1 Product 2 Product 3
A 1.95 3.45 2.45
B 2.90 1.90 3.40
C 0.70 0.70 0.70

During the next production period, the labor-hours available are 540 in department A, 440 in department B, and 140 in department C. The profit contributions per unit are $34 for product 1, $37 for product 2, and $39 for product 3.

(a) Formulate a linear programming model for maximizing total profit contribution. For those boxes in which you must enter subtractive or negative numbers use a minus sign. (Example: -300)
Let Pi = units of product i produced.

(b) Solve the linear program formulated in part (a). How much of each product should be produced, and what is the projected total profit contribution?
(c) After evaluating the solution obtained in part (b), one of the production supervisors noted that production setup costs had not been taken into account. She noted that setup costs are $490 for product 1, $640 for product 2, and $690 for product 3. If the solution developed in part (b) is to be used, what is the total profit contribution after taking into account the setup costs?
(d) Management realized that the optimal product mix, taking setup costs into account, might be different from the one recommended in part (b). Formulate a mixed-integer linear program that takes setup costs into account. Management also stated that we should not consider making more than 220 units of product 1, 195 units of product 2, or 185 units of product 3. For those boxes in which you must enter subtractive or negative numbers use a minus sign. (Example: -300)
Here introduce a 0-1 variable yi that is one if any quantity of product i is produced and zero otherwise.
(e) Solve the mixed-integer linear program formulated in part (d). How much of each product should be produced, and what is the projected total profit contribution? Compare this profit contribution to that obtained in part (c).