OH variances The manager of the Texas Department of Transportation has determined that it typically takes 30 minutes for the department's employees to register a new car. In Bexar County, the predetermined fixed overhead rate was computed on an estimated 4,000 direct labor hours per month and is $9 per direct labor hour, whereas the predetermined variable overhead rate is $3 per direct labor hour. During July, 7,520 cars were registered in Bexar County, and 3,800 direct labor hours were worked in registering those vehicles. For the month, variable overhead was $11,080 and fixed overhead was $36,320. Note: In answering the following questions, do not use negative signs with your answers. a. Compute overhead variances using a four-variance approach. b. Compute overhead variances using a three-variance approach. c. Compute overhead variances using a two-variance approach