The Beef-up ranch feeds cattle for midwestern farmers and delivers them to processing plants in Topeka, Kansas and Tulsa, Oklahoma. The ranch must determine the amounts of cattle feed to buy so that various nutritional requirements are met while minimizing total feed costs. The mixture fed to the cows must contain different levels of four key nutrients and can be made by blending three different feeds. The amount of each nutrient (in ounces) found in each pound of feed is summarized as follows:

Nutrient

a- feed 1 (3) feed 2 (2) feed 3 (4)

b- feed 1 (3) feed 2 (1) feed 3 (3)

c- feed 1 ( 1) feed 2 (0) feed 3 (2)

d- feed 1 (6) feed 2 (8) feed 3 (4)

The cost per pound of feeds 1, 2, and 3 are $2.00, $2.50, and $3.00, respectively. The minimum requirement per cow each month is 4 pounds of nutrient A, 5 pounds of nutrient B, 1 pound of nutrient C, and 8 pounds of nutrient D. However, cows should not be fed more than twice the minimum requirement for any nutrient each month. Additionally, the ranch can only obtain 1,500 pounds of each type of feed each month. Because there are usually 100 cows at the beef-up ranch at any given time, this means that no more than 15 pounds of each type of feed can be used per cow each month.

a. Formulate a linear programming problem to determine how much of each type of feed a cow should be fed each month.

b. Create a spreadsheet model for this problem, and solve it using Solver.

c. What is the optimal solution?