Problem 9-12 Change in methods ILO9-61 Rockwell Corporation uses a periodic inventory system and has used the FlFO cost method since inception of the company in 1979. In 2016, the company decided to switch to the average cost method. Data for 2016 are as follows: Beginning inventory, FIFO (7,400 units $28) $207,200 Purchases $251,600 7,400 units $34 7,400 units $38 281,200 532,800 $740,000 Cost of goods available for sale $680,000 Sales for 2016 (10,000 units $68) Additional Information: a. The company's effective income tax rate is 40% for all years. b. If the company had used the average cost method prior to 2016, ending inventory for 2015 would have been $177,600 c. 12,200 units remained in inventory at the end of 2016