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Periodic Inventory by Three Methods The units of an item avaliable for sale during the year were as follows: There are 9 units of the item in the phyrical inventory at Decembar 21. The periodic inventory syatem is used. a. Determine the inventary cost by the firit-in, first out method. x b. Determine the imventory coot by the iastin, fint-out method: x C. Ootorinine the inweatior cont by the weighised average coit method. Round average unit cost to the nearest cent and final answers to the aearest whale dollar, if regulesed