Graham Manufacturing designs and manufactures sinks for home and commercial applications. Graham Manafacturing recorded the following data for its commercial sink production line during the month of March: 5 Standard DL hours per sink Standard overhead rate per DL hour Standard overhead cost per unit $6.00 $30.00 Actual overhead costs Actual DL hours Actual overhead cost per machine hour $21,375 2850 $7.50 Actual sinks produced 1500 What is the variable manufacturing overhead efficiency variance in March? $4275 unfavorable $4275 favorable $27.900 favorable $27.900 unfavorable