The following labor standards have been established for a particular product: standard labor hours per unit of output 4.5 hours standard labor rate $ 20.30 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 $ 144,840 actual output 1,500 units required: a. what is the labor rate variance for the month? b. what is the labor efficiency variance for the month? (indicate the effect of each variance by selecting "f" for favorable, "u" for unfavorable, and "none" for no effect (i. e., zero variance). input all amounts as positive values.)