Periodic Inventory by Three Methods The units of an item available for sale during the year were as follows: Jan. 1 Inventory 4 units $25 Feb 17 Purchase 18 units $27 July 21 Purchase 5 units $30 Nov. 23 Purchase 18 units $32 There are 4 units of the item in the physical inventory at December 31. The periodic inventory system is used .. Determine the inventory cost by the first in first-out method, 3. Determine the inventory cost by the lastnost-out method 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