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Periodic inventory by three methods The units of an item available for sale during the year were as follows: Jan. 1 Inventory 5,500 units at $4 Feb. 17 Purchase 6,400 units at $6 July 21 Purchase 6,000 units at $8 Nov. 23 Purchase 2,100 units at $10 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. Round average unit cost to two decimal places