Question: how to calculate ending inventory fifo method?
Answer: Ending Inventory per LIFO: 1,000 units x $8 = $8,000. ... 
Ending Inventory per FIFO: 1,000 units x $15 each = $15,000. ... 
Ending Inventory per Average Cost: (1,000 x 8) + (1,000 x 10) + (1,000 x 12) + (1,000 x 15)] / 4000 units = $11.25 per unit; 1,000 units X $11.25 each = $11,250.