The following labor standards have been established for a particular product: Standard labor hours per unit of output 4.2 hours Standard labor rate $ 20.00 per hours The following data pertain to operations concerning the product for the last month: Actual hours worked 6,800 hours Actual total labor cost $ 136,680 Actual output 1,600 units Required: a. What is the labor rate variance for the month? U or F b. What is the labor efficiency variance for the month U or F?