Periodic Inventory by Three Methods The units of an item available for sale during the year were as follows: Jan. 1 Inventory 15 units @ $24 Feb. 17 Purchase 14 units @ $26 July 21 Purchase Nov. 23 Purchase 4 units $28 20 units $29 There are 15 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 the nearest cent and final answers to the nearest whole dollar, if required.