a Beginning inventory, purchases, and sales data for watches are as follows: Inventory Purchases Sales May 1 850 units at $112 May 8 320 units at $120 May 10 600 units 19 98 units at $132 15 405 units 30 172 units a. Assuming that a perpetual inventory system is used, costing by the FIFO method, determine the cost of goods sold for each sale and the inventory balance after each sale, presenting the data in the form illustrated in Exhibit 3, on page 310. b. Assuming that the perpetual inventory system is used, costing by the weighted average method, determine the cost of goods sold for each sale and the inventory balance after each sale, presenting the data in the form illustrated in Exhibit 4, on page 311. 11