Mirabile Corporation uses activity-based costing to compute product margins. Overhead costs have already been allocated to the company's three activity cost pools--Processing, Supervising, and Other. The costs in those activity cost pools appear below: Processing $ 5880 Supervising $ 33,600 Other $ 12,100 Processing costs are assigned to products using machine-hours (MHS) and Supervising costs are assigned to products using the number of batches. The costs in the Other activity cost pool are not assigned to products. Activity data appear below: Product MO MHs (Processing) Batches (Supervising) 11,400 800 600 800 12,000 1600 Product M5 Total Finally, sales and direct cost data are combined with Processing and Supervising costs to determine product margins. Sales (total) Direct materials (total) Direct labor (total) Product MO Product M5 $86,300 $98,400 $30,200 $33,100 $29,500 $43,400 The activity rate for the Supervising activity cost pool under activity-based costing is closest to: $7.35 per batch $21.00 per batch $28.56 per batch $24.68 per batch