Question 2 (20 pts): The Battery Park Stable feeds and houses horses used to pull tourist-filled carriages through the streets of Charlestons historic waterfront area. The stable owner, an ex-racehorse trainer, recognizes the need to set a nutritional diet for the horses in his care. At the same time, he would like to keep the overall daily cost of feed to a minimum. The feed mixes available for the horses diet are an oat product, a highly enriched grain, and a mineral product. Each of these mixes contains a certain amount of five ingredients (labeled as A, B, C, D, and E) needed daily to keep the average horse healthy. The table below shows these minimum requirements, units of each ingredient per pound of feed mix, and costs for the three mixes. In addition, the stable owner is aware that an overfed horse is a sluggish worker. Consequently, he determines that 6 pounds of feed per day are the most that any horse needs to function properly.

Diet Requirement	Feed Mix	Feed Mix	Feed Mix	Feed Mix
	Oat Product (Units/LB)	Enriched Grain (Units/LB)	Mineral Product (Units/LB)	Minimum Daily Requirement (Units)
A	2	3	1	6
B	0.5	1	0.5	2
C	3	5	6	9
D	1	1.5	2	8
E	0.5	0.5	1.5	5
Cost/LB	$0.09	$0.14	$0.17

a) (4 pts) Is this a maximization or a minimization problem? What is the objective?

b) (8 pts) Formulate this problem mathematically. Use X1, X2, and X3 to represent the amount of oat product, enriched grain, and mineral product, respectively. Write down or type the objective function and all constraints clearly. (Dont forget the nonnegativity constraints when applicable.)

(c) (8 pts) Set up this problem in Excel and use Solver to find the optimal daily mix of the three feeds, i.e., the optimal value for X1, X2, and X3.