Periodic Inventory by Three Methods The units of an item available for sale during the year were as follows: Jan. 1 Inventory Feb. 17 Purchase July 21 Purchase Nov. 23 Purchase 10 units @ $27 18 units @ $29 15 units @ $30 20 units @ $31 There are 10 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 an dollar, if required. All work saved