Reddick's Specialty Electronics makes weatherproof surveillance systems for parking lots. Demand estimates for the next four quarters are 25, 9, 13, and 17 units. The firm is preparing an aggregate plan that uses inventory, regular time and overtime and back orders to satisfy demand. Subcontracting is not allowed. Beginning inventory is zero. Regular time capacity is 15 units for quarters 1 and 2, 18 units for quarters 3 and 4. Overtime capacity is 3 units per quarter. Regular time cost is $2000 per unit, while overtime cost is $3000 per unit. Back order cost is $300 per unit per quarter; inventory holding cost is $100 per unit per quarter. 1. Develop a mathematical model to satisfy demand at a minimal cost 2. Construct an Excel model to solve for the optimal solution