Cost Flow Methods The accounting records of Shumway Ag Implements show the following data. ns.! Beginning inventory. Purchases Sales 4,000 units at $ 3 6,000 units at $ 4 7,000 units at $12 Determine the cost of goods sold during the period under a periodic inventory system using (a) the FIFO method, (b) the LIFO method, and (c) the average-cost method. Solution