II. P6-4A. Inventory Costing Methods-- Periodic Method Chou Sales Corporation uses the periodic inventory system. On January 1, 2018, Chen had 2,000 units of product A with a unit cost of $10 per unit. A summary of purchases and sales during 2018 follows: Units Unit Cost Purchased Units Sold Feb. 2. 1,000 Apr. 6 $30 2,000 July 10 2,000 Aug. 9 40 3,000 Oct. 23 3,000 Dec. 30 50 2,000 Required Assuming that the periodic inventory method is used, compute (a) the Cost of Goods Sold and (b) Ending Inventory under (1) LIFO. (2) WA and (3) FIFO