Chester Inc. uses a periodic inventory system. Its records show the following for the month of August, in which 325 units were sold: Date Number of units Cost per unit Total cost September 1 Inventory, beginning 300 $18 $5,400 September 15 Purchase 250 $20 $5,000 September 29 Purchase 100 $22 $2,200 Total 450 $12,600 Compute cost of goods sold for the month of August assuming that Chester Inc. uses the first-in, first-out (FIFO) inventory costing method