The units of Manganese Plus available for sale during the year were as follows: Mar. 1 Inventory 22 units $660 @ $30 June 16 31 units 961 @ $31 Purchase Purchase Nov. 28 40 units @ $38 1,520 93 units $3,141 There are 16 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