Wilco's production and cost data for the first six months are presented below: Month January February March April May June Cost $11,000 $10,800 $12,500 $13,200 $13,000 $11,850 Units Produced 6,000 6,500 8,000 11,500 12,200 9,000 Use the high-low method to calculate Wilco's variable cost per unit.