Kropf Incorporated has provided the following data concerning one of the products in its standard cost system. Variable manufacturing overhead is applied to products on the basis of direct labor-hours. The company has reported the following actual results for the product for September: Required: a. Compute the materials price variance for September. b. Compute the materials quantity variance for September. c. Compute the labor rate variance for September. d. Compute the labor efficiency variance for September. e. Compute the variable overhead rate variance for September. f. Compute the variable overhead efficiency variance for September