OBJ. 2,4 EX 7-12 Periodic inventory by three methods The units of an item available for sale during the year were as follows: Jan. Feb. 17 July 21 Nov. 23 Inventory Purchase Purchase Purchase 1,000 units at $120 1,375 units at $128 1,500 units at $136 1,125 units at $140 There are 1,200 units of the item in the physical inventory at December 31. The periodic inventory system is used. Determine the inventory cost by (a) the first-in, first-out method; (b) the last-in, first-out method; and (c) the weighted average cost method