Periodic Inventory by Three Methods The units of an item available for sale during the year were as follows 7537 Jan. 1 Inventory Feb 17 Purchase 6 units $38 13 units $40 Jul 21 Purchase Nov. 23 Purchase 17 units $42 There are 7 units of the them in the physical inventury at December 31. The periodic inventory system is used. Round average unit cost to the nearest cent and final answers to the nearest whole dollar if required. a. Determine the inventory cost by the first in, first-out method. b. Determine the inventory cost by the last-in, first-out method Determine the inventory cost by the weighted average cost method