A B Volume (Units) Series A Series B Following are four series of costs measured at various volume levels. Identify each series as either fixed. Exercise 18-3 variable, mixed, or step-wise. Hint: It can help to graph each cost series. Identifying cost type C1 D Series C Series D 1 0 $ 0 $2,500 $1,000 234567 400 $5,000 3,600 3,100 1,000 5,000 800 7,200 3,700 Excel 2,000 5,000 1,200 10,800 Enter data 4,300 2,000 5,000 1,600 Select 14,400 4,900 3,000 5,000 Insert 2,000 18,000 5,500 3,000 5,000 Charts 2,400 21,600 6,100 4,000 All Charts 5,000 Line Coccify auch of the full