The units of an item available for sale during the year were as follows: Jan 1 Inventory 27 units at $120 Feb 17 Purchase 54 units at $138 July 21 Purchase 63 units at $156 Nov 23 Purchase 36 units at $165 There are 50 units of the item in the physical inventory at December 31. The periodic inventory system is used. Determine the inventory cost by (a) FIFO, (b) LIFO and (c) the Average cost method