The units of Manganese Plus available for sale during the year were as follows: $667 Mar. 1 June 16 Nov. 28 Inventory Purchase Purchase 23 units 29 units 38 units @ $29 @ $31 @ $36 899 1,368 90 units $2,934 There are 14 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