Given the projected demands for the next six months, prepare an aggregate plan that uses inventory, regular time and overtime, subcontracting and backorders. The plan must wind up with no units in ending inventory in Period 6. Regular time capacity is 150 units per month. Overtime capacity and subcontracting capacity are 20 units per month each. Overtime cost is $30 per unit, subcontracting cost is 40 per unit, and backorder cost is $20 per unit, inventory holding cost is $5 per unit, regular time cost of $20 per unit, and beginning inventory is zero. month forecast

1 180

2 170

3 140

4 150

5 130

6 150