Harris Corporation is a wholesaler that sells a single product. Management has provided the following cost data for two levels of monthly sales volume. The company sells the product for $84.40 per unit. The best estimate of the total variable cost per unit is: $77.00 $57.00 $69.50 $78.50 A partial listing of costs incurred during December at Rooks Corporation appears below: The total of the product costs listed above for December is: $647,000 $307,000 $340,000 $82,000