Sheffield Corp. had a beginning inventory of 115 units of Product RST at a cost of $9 per unit. During the year, purchases were: Feb. 20 660 units at $10 Aug. 12 401 units at $12 May 5 559 units at $11 Dec. 8 115 units at $13 Sheffield uses a periodic inventory system. Sales totaled 1,500 units. (a) Your answer is correct. Determine the cost of goods available for sale. The cost of goods available for sale 20091 Calculate Average Cost. (Round answer to 3 decimal places, e.g. 5.125.) Average Cost $ 10.860