The standards for one case of springfever tonic are: direct materials 5.50 lbs @ $4.50/lb = $ 24.75 direct labor 4.50 hrs @ $11.50/hr = 51.75 variable overhead (based on direct labor hours) 4.50 hrs. @ $5.50/hr = 24.75 during the week ended march 28, the following activity took place: 18,500 lbs. of raw materials were purchased for inventory at a cost of $4.45 per pound. 2,900 cases of finished product were produced. 17,000 lbs. of raw materials were used. 12,900 direct labor hours were worked at a total cost of $167,700. $76,110 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.) a. price variance for raw material purchased b. raw materials usage variance c. direct labor rate variance d. direct labor efficiency variance e. variance overhead spending variance f. variable overhead efficiency variance.