The units of Manganese Plus available for sale during the year were as follows: Mar. 1 June 16 Inventory Purchase Nov. 28 Purchase 20 units 28 units @$31 $620 $34 952 42 units 90 units @ $37 1,554 $3,126 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.