You would like to construct an aggregate production plan for product X341 for the next four quarters. Cost of regular production = 60 $/u Cost of overtime production = 90 $/u Inventory holding cost = 10 $/u/qtr Cost of increasing production = 70 $/u Cost of decreasing production = 120 $/u Subcontracting cost = 115 $/u Stockout cost = 130 $/u Previous quarter's regular output = 600 u Beginning inventory level = 120 u The forecasted demand for the next four quarters are: 500, 1000, 400, and 1200 units. Suppose that you want to set the quarterly regular production constant at 680 units and to use overtime if necessary.