New jersey valve company manufactured 7,800 units during january of a control valve used by milk processors in its camden plant. records indicated the following: direct labor 40,200 hr. at $14.60 per hr. direct material purchased 30,000 lb. at $3.00 per lb. direct material used 22,100 lb. the control valve has the following standard prime costs: direct material 3 lb. at $2.90 per lb. $ 8.70 direct labor 5 hr. at $15.10 per hr. 75.50 standard prime cost per unit $ 84.20 required: prepare a schedule of standard production costs for january, based on actual production of 7,800 units. for the month of january, compute the following variances.