Inventory Costing Methods-Periodic Method The Gleem Sales Corporation uses the periodic inventory system. On January 1, 2012, Gleem had: 2,600 units of product B with a unit cost of $120 per unit. A summary of purchases and sales during 2012 follows: Jan.3 Mar.8 Unit Units Units Cost Purchased Sold 1,600 $124 3,000 2,000 130 800 June 13 Sept. 19 Nov.23 135 1,200 Dec.28 1,800 Required a. Assume that Gleem uses the first-in, first-out method. Compute the cost of goods sold for 2012 and the ending inventory balance at December 31, 2012, for product B. b. Assume that Gleem uses the last-in, first-out method. Compute the cost of goods sold for 2012 and the ending inventory balance at December 31, 2012, for product B. C. Assume that Gleem uses the weighted average cost method. Compute the cost of goods sold for 2012 and the ending inventory balance at December 31, 2012, for product B