Ford has four automobile plants. Each is capable of producing the Focus, Mustang, or Crown Victoria, but it can produce only one of these cars. The fixed cost of operating each plant for a year and the variable cost of producing a car of each type at each plant are given in the file P06_59.xlsx. Ford faces the following restrictions:

■ Each plant can produce only one type of car.

■ The total production of each type of car must be at a single plant. For example, if any Mustangs are made at plant 1, then all Mustangs must be made there.

■ Each year, Ford must produce 5 million of each type of car.

a. Determine how to minimize the annual cost of producing these cars.

b. Use SolverTable to see how a change in the demand for a type of car changes the optimal solution. Do this separately for each type of car.

c. Use SolverTable to see how the optimal solution is affected by a change in the variable cost of producing a Focus at plant 4.