Periodic Inventory by Three Methods The units of an item available for sale during the year were as follows: Jan. 1 Feb. 17 Inventory Purchase Purchase 2,500 units at $5 3,300 units at $6 3,000 units at $7 July 21 Nov. 23 Purchase 1,200 units at $8 There are 1,500 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. $