The following standards for variable manufacturing overhead have been established for a company that makes only one product: 1.6 hours $11.55 per hour Standard hours per unit of output..... The following data pertain to operations for the last month: Actual hours... Actual total variable manufacturing ovethead cost 4.900 hours . $58.310 3,000 units What is the variable overhead efficiency variance for the month? O $1,680 F O $1,190 U O $1,155 U $1,190 F