Sheridan Company's overhead rate was based on estimates of $168,000 for overhead costs and 16,800 direct labour hours. Sheridan's standards allow 2 hours of direct labour per unit produced. Production in May was 750 units, and actual overhead incurred in May was $19,000. The overhead budgeted for 1,500 standard direct labour hours is $14,700 ( $4,200 fixed and $10,500 variable). (a) Calculate the total, budget, and volume variances for overhead