Periodic Inventory Using FIFO, LIFO, and Weighted Average Cost Methods The units of an item available for sale during the year were as follows: There are 20 units of the item in the physical inventory at December 31. The periodic inventory system is used. Determine the inventory cost usi dollar). Feedback T Check My Work a. When the FIFO method is used, costs are included in cost of goods sold in the order in which they were purchased. b. When the LIFO method is used, the cost of the units sold is the cost of the most recent purchases. c. The average cost method is sometimes called the weighted average method. The average cost method uses the average unit cost for determ