Periodic Inventory by Three Methods The units of an item available for sale during the year were as follows: Jan. 1 Inventory 1,095 units $138 Feb. 17 Purchase 1,410 units $140 Jul. 21 Purchase 1,620 units @ $141 Nov. 23 Purchase 1,140 units $143 There are 1,215 units of the item in the physical inventory at December 31. The periodic inventory system is used. Do not round intermediate calculation and round final answer to nearest whole value a. Determine the inventory cost by the first-in, first-out method. b. Determine the inventory cost by the last in, first out method. c. Determine the inventory cost by the weighted average cost method