Blue Spruce Company's overhead rate was based on estimates of $188,400 for overhead costs and 18,840 direct labour hours. Blue Spruce's standards allow 2 hours of direct labour per unit produced. Production in May was 840 units, and actual overhead incurred in May was $19,000. The overhead budgeted for 1,680 standard direct labour hours is $16,470 ( $4,710 fixed and $11,760 variable). (a) Calculate the total, budget, and volume variances for overhead