The units of an item available for sale during the year were as follows: January 10 February 27 July 11 November 13 Inventory Purchase Purchase Purchase 27 units @ $90 54 units @ $98 63 units @ $106 36 units @ $115 There are 50 units of the item in the physical inventory at December 31. The periodic inventory system is used. a. Determine the ending inventory cost by the first-in, first-out method. b. Determine the ending inventory cost by the last-in, first-out method. c. Determine the ending inventory cost by the average cost method