The standard cost of each batch consists of 8,000 pounds of direct materials at $0.40 per pound, 48 direct labor hours at $8.75 per hour, and variable overhead cost (based on machine hours) at the rate of $10 per hour with 16 machine hours per batch. The following variable costs were incurred for the last 1,000-bag batch produced: Direct materials 8,300 pounds costing $ 3,154 were purchased and used Direct labor 45 hours costing $ 450 Variable overhead $ 225 Machine hours used 18 hour (a) Determine the actual and standard variable costs per bag of dog food produced, separated into direct materials, direct labor, and variable overhead. (b) For the last 1,000-bag batch, determine the standard cost variances for direct materials, direct labor, and variable overhead