The static budget, at the beginning of the month, for Shirley Company follows:
Static budget:
Sales volume: 2000 units: Sales price: $57.00 per unit
Variable cost: $12.00 per unit: Fixed costs: $25,000 per month
Operating income: $65,000
Actual results, at the end of the month, follows:
Actual results:
Sales volume: 1800 units: Sales price: $58.00 per unit
Variable cost: $18.00 per unit: Fixed costs $36,000 per month
Operating income: $36,000
Calculate the sales volume variance for variable costs.