The units of Manganese Plus available for sale during the year were as follows: Mar. 1 Inventory 25 units $30 750 June 16 Purchase30 units$33 Nov. 28 Purchase 42 units$38 990 97 units $3,336 There are 15 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