Vaughn Company's inventory records show the following data: Unit Units Cost Inventory, January 1 11000 $8.80 Purchases: June 18 5000 8.00 November 8 4000 6.00 A physical inventory on December 31 shows 3500 units on hand. Vaughn sells the units for $14 each. The company has an effective tax rate of 18%. Vaughn uses the periodic inventory method. The weighted average cost per unit is O $7.80. O $8.04. O $7.81. O $8.90.