Olivet Devices sells two models of fitness devices. The budgeted price per unit for the wireless model is $38 and the budgeted price per unit for the wireless and cellular model is $83. The master budget called for sales of 40,000 wireless models and 10,000 wireless and cellular models during the current year. Actual results showed sales of 31,000 wireless models, with a price of $35 per unit, and 12,000 wireless and cellular models, with a price of $80 per unit. The standard variable cost per unit is $25 for a wireless model and $60 for a wireless and cellular model. 

Required

a. Compute the sales activity variance for these data.

b. Break down the sales activity variance into mix and quantity parts.