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Periodic inventory using FIFO, LIFO, and weighted average oost 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, firstout (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 final answer to the nearest whole dollar). a. First-in, first-out (FIFO) method $ b. Last-in, first-out (LIFO) method it c. Weighted average cost method