Ferris company began january with 7,000 units of its principal product. the cost of each unit is $6. merchandise transactions for the month of january are as follows: purchases date of purchase units unit cost* total cost jan. 10 6,000 $ 7 $ 42,000 jan. 18 7,000 8 56,000 totals 13,000 98,000 * includes purchase price and cost of freight. sales date of sale units jan. 5 3,000 jan. 12 1,000 jan. 20 4,000 total 8,000 12,000 units were on hand at the end of the month. 3. calculate january's ending inventory and cost of goods sold for the month using fifo, perpetual system.