Problem 8-5 Various inventory costing methods [LO8-1, 8-4] Ferris Company began 2018 with 6,000 units of its principal product. The cost of each unit is $5. Merchandise transactions for the month of January 2018 are as follows Purchases Unit Cost* Total Cost Date of Purchase Jan. 10 Jan. 18 Units 5,000 6,000 11,000 $30,000 42,000 72,000 Totals Includes purchase price and cost of freight. Sales Date of Sale Jan. !5 Jan. 12 Jan. 20 Units 3,000 2,000 4,000 9,000 Total 8,000 units were on hand at the end of the month Required: Calculate January's ending inventory and cost of goods sold for the month using each of the following alternatives