The Poole Corporation has a standard costing system in which variable manufacturing overhead is assigned to production on the basis of standard machine-hours. The following data are available for July Actual variable manufacturing overhead cost incurred: $11,310 Actual machine-hours worked: 1,600 hours Variable overhead rate variance: $1.710 U Total variable overhead spending variance: $2,310 U The variable overhead efficiency variance for July is: OA $540 F OB $540 U OC. $600 F D. $600 U Clear my choice