Periodic Inventory by Three Methods The units of an item available for sale during the year were as follows: Jan. 1 Inventory 1,000 units at $120 Feb. 17 Purchase 1,375 units at $128 July 21 Purchase 1,500 units at $136 Nov. 23 Purchase 1,125 units at $140 There are 1,200 units of the item in the physical inventory at December 31. The periodic inventory system is used. 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