The following standards for variable overhead have been established for a company that makes only one product: Standard hours per unit of output Standard variable overhead rate 5.4 hours $14.00 per hour The following data pertain to operations for the last month 9,100 hours Actual hours Actual total variable overhead cost Actual output $125,090 1,670 units Required a. What is the variable overhead rate variance for the month? (Input the amount as a positive value Leave no cells blank - be certain to enter "O" wherever required. Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance.] anable overhead ra variance b. What is the variable overhead efficiency variance for the month? (Input the amount as a positive value. Leave no cells blank - be certain to enter "O" wherever required. Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance.] anable overhead efficiencv vanance