Cullumber Company uses a perpetual inventory system. The company began 2024 with 1,000 lamps in inventory at a cost of $10 per unit. During 2024, Cullumber had the following purchases and sales of lamps: February 15 Purchased 2,000 units @ $16 per unit April 24 Sold 2,500 units @ $28 per unit June 6 Purchased 3,500 units @ $21 per unit October 18 Sold 2,000 units @ $31 per unit December 4 Purchased 1,400 units @ $24 per unit All purchases and sales are on account.