DE21-24 + Link Back to Chapter 9 (Difference Between FIFO and Weighted Average). For Polar Spring's Bottling Department, use your answers to Daily Exercise 21-18 and Daily Exercise 21-22 to compare the cost of the units completed and transferred out under FIFO to that under weighted-average. Compare the cost of the Bottling Department's ending work in process inventory under FIFO to that under weighted average. Did the Bottling Department cost per unit increase or decrease in February? How do you know?