Analyzing and Interpreting the Financial Statement Effects of Periodic FIFO. UFO. and Weighted Average Cost [LO 7-3] Orion Iron Corp. tracks the number of units purchased and sold throughout each year but applies its inventory costing method at the end of the year, as if it uses a periodic inventory system Assume its accounting records provided the following information at the end of the annual accounting period. December 31. Calculate the number and cost of goods available for sale. Calculate the number of units in ending inventory