Current Attempt in Progress Barbara Corp. purchased inventory as follows: March 3 540 units at $18 March 4 360 units at $20 March 7 210 units at $22 On March 5, Barbara sold 750 units for $18 each. The average unit cost to be used for the cost of goods sold on March 5, in a perpetual inventory system, is O $22.56. O $15.24. O $18.80. O $19.41