Periodic Inventory Using FIFO, UFO, and Weighted Average Cost Methods The units of an item available for sale during the year were as follows: There are 21 units of the item in the physical inventory at December 31. The periodic inventory system is used. Determine the inventory cost using the (a) first-in, first. out (FIFO) method; (b) last-in, first-out (LIFO) method; and (c) weighted average cost method (round per-unit cost to two decimal places and your finat answer to the