The standards for one case of Springfever Tonic are as follows: Direct materials Direct labor Variable overhead (based on direct labor hours) 6.10 lb @ $ 5.10/lb = $31.11 5.10 hr @ $12.10/hr = $61.71 5.10 hr @ $ 6.10/hr = $31.11 During the week ended August 28, the following activity took place: 21,500 lb of raw materials were purchased for inventory at a cost of $5.05 per pound. 2,800 cases of finished product were produced. 17,500 lb of raw materials were used. 13,500 direct labor hours were worked at a total cost of $183,600. $81,000 of actual variable overhead costs were incurred. Required: Calculate each of the following variances. (Do not round intermediate calculations. Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance).) a. Price variance for raw materials purchased. b. Raw materials usage variance C Direct labor rate variance. d. Direct labor efficiency variance. e. Variable overhead spending variance. f. Variable overhead efficiency variance