Calculation of ending inventory and COGS using FIFO vs. LIFO vs. Average Cost and the underlying assumptions of each method Calculation of ending inventory and COGS using FIFO: Underlying assumptions of FIFO: Calculation of ending inventory and COGS using LIFO: Underlying assumptions of LIFO: Calculation of ending inventory and COGS using Average Cost: Underlying assumptions of Average Cost: Calculation of ending inventory and COGS using FIFO vs. LIFO vs. Average Cost and the underlying assumptions of each method Calculation of ending inventory and COGS using FIFO: Underlying assumptions of FIFO: Calculation of ending inventory and COGS using LIFO: Underlying assumptions of LIFO: Calculation of ending inventory and COGS using Average Cost: Underlying assumptions of Average Cost