Formulating a linear programming model for this problem of United Aluminum Company of Cincinnati:

• The objective is to minimize the cost of operating the mills while meeting the contract requirements.
• Lex X1 be the number of days to operate the mill 1, and x2 be the number of days to operate mill 2.

Decision Variables:

• X1: Number of days to operate Mill 1
• X2: Number of days to operate Mill 2

Objective Function:

• Z= 6000x1 + 7000x2

Constraints:

Production Requirements: Aluminum grade:

• High: 6x1 + 2x2 >= 12
• Medium: 2x1 + 2x2>= 8
• Low: 4x1 + 10x2>= 5

Non-negativity:

• X1>=0, X2>=0

• The objective function minimizes the mills' overall operating costs.
• Each constraint guarantees that the overall output of each aluminum grade equals or exceeds the stipulated quantity.
• The non-negativity condition assures that the number of days of operation is not negative.

This linear programming model will assist the United Aluminum Company of Cincinnati in determining the ideal number of operating days for each mill while satisfying contract criteria at the lowest possible cost.

Solve the linear programming model formulated in Problem 1 for United Aluminum Company by using the computer.

a. Identify and explain the shadow prices for each of the aluminum grade contract requirements.

b. Identify the sensitivity ranges for the objective function coefficients and the constraint quantity values.

c. Would the solution values change if the contract requirements for high-grade aluminum were increased from 12 tons to 20 tons? If yes, what would the new solution values be?