Sara's Systems manufactures audio systems for cars. Two models are produced: The Standard model has a budgeted price of $190 and a standard variable cost of $70. The Blaster model has a budgeted price of $470 and a standard variable cost of $150. At the beginning of the year, Sara estimated that she would sell 5,960 Blaster models and 23,840 Standard models. The actual results for the year showed that 7,470 Blaster models were sold for total revenues of $3,585,600. A total of 26,900 Standard models were sold for revenues of $6,994,000. Required: a. Compute the volume variance (also known as activity variance) for the year. (Do not round intermediate calculations. Indicate the effect of each variance by selecting "F" for favorable, or "U" for unfavorable. If there is no effect, do not select either option.) Activity variance