Cox Engineering performs cement core tests in its laboratory. The following standards have been set for each core test performed: Std. Hours or Quantity Std. Price or Rate Direct materials 3 pounds $0.75 per pound Direct labor 0.4 hours $12 per hour During March the laboratory performed 2,000 core tests. The following events occurred during March: 8,600 pounds of sand were purchased at a cost of $7,310. 7,200 pounds of sand were used for core tests. 840 actual direct labor hours were worked at a cost of $8,610. The direct material usage variance for March is: