2.The units of Manganese Plus available for sale during the year were as follows: Mar. 1 Inventory 20 units @ $30 $600 June 16 Purchase 30 units @ $33 990 Nov. 28 Purchase 39 units @ $38 1,482 89 units $3,072 There are 13 units of the product in the physical inventory at November 30. The periodic inventory system is used. Round answers to the nearest whole dollar. a. Determine the inventory cost by the FIFO method. $ b. Determine the inventory cost by the LIFO method. $ c. Determine the inventory cost by the average cost methods.