281 PE 6-5B 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 Aug. 13 Nov. 30 Inventory Purchase Purchase Available for sale 20 units at $360 $ 7,200 260 units at $342 88,920 40 units at $357 14,280 320 units $110,400 OBJ. 4 There are 57 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) method; and (c) the weighted average cost method.