The following information is for Lockheed Company for the month of May. Lockheed uses a perpetual inventory system: May 1 100 units were purchased at $10 per unit May 5 200 units were purchased at $20 per unit May 12 200 units were purchased at $40 per unit May 23 250 units were purchased at $30 per unit May 28 610 units were sold for $80 per unit Required: Calculate Lockheed Company's ending inventory and cost of goods sold using the each of following inventory costing methods. a. FIFO b. LIFO c. Weighted Average