Periodic Inventory Using FIFO, LIFO, and Weighted Average Cost Methods The units of an item available for sale during the year were as follows: Jan. 1 Inventory 8 units at $3,500 $28,000 Aug. 7 Purchase 20 units at $3,700 74,000 Dec. 11 Purchase 10 units at $3,900 39,000 38 units $141,000 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, first-out (FIFO) method; (b) the last-in, first-out (LIFO