inventory costing methods crandall distributors uses a perpetual inventory system and has the following data available for inventory, purchases, and sales for a recent year: activity units purchase price (per unit) sale price (per unit) beginning inventory 110 $7.10 purchase 1, jan. 18 575 7.20 sale 1 380 $12.00 sale 2 225 12.00 purchase 2, mar. 10 680 7.50 sale 3 270 12.00 sale 4 290 12.50 purchase 3, sept. 30 230 7.70 sale 5 240 12.50