Periodic Inventory by Three Methods The units of an item avalable for sale during the yean were as follows: There are 10 units of the item in the physical imventary at December 31. The periodic inventery system is used. Round average unit cost to the nearest cent and final answers to the nearest whalo dolar, if required. a. Determine the inventory cost by the first-in, frat-out method. 1 b. Determine the imventory cost by the last-in, fint-out method. c. Determine the inventory cost by the weighted average cost method