The following labor standards have been established for a particular product: Standard labor-hours per unit of output 9.3 hours Standard labor rate $ 13.10 per hour The following data pertain to operations concerning the product for the last month: Actual hours worked 7,100 hours Actual total labor cost $ 90,170 Actual output 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