33. The following labor standards have been established for a particular product: hours Standard labor-hours per unit of output Standard labor rate per hour The following data pertain to operations concerning the product for the last month: hours Actual hours worked Actual total labor cost Actual output 7,100 $90,170 1,000 units What is the labor efficiency variance for the month? a. $31,660 F b. $31,660 U c. $27,940 F d. $28,820 F