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 18 units of the item in the physical inventory at December 31 . The periodic inventory system is used. Determine the inventory cost using (a) the first-in, out (FIFO) method; (b) the last-in, first-out (LIFO) method; and (c) the 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) $ b. Last-in, first-out (LIFO) $ c. Weighted average cost