Feb. 17 Purchase 14 units at $42 Jul 21 Purchase 18 units at $45 Nov. 23 Purchase 5 units at $45 There are 10 units of the item in the physical inventory at December 31. The periodic inventory system is used. Round average unit cost to the nearest cent and final answers to the nearest whole dollar, if required a. Determine the inventory cost by the first in first-out method b. Determine the inventory cost by the last first-out method c. Determine the inventory cost by the weighted average cost method