NSF Lube is a fast-growing chain of oil-change stores. The following data are available for last year's services: NSF Lube performed 468,200 oil changes last year. It had budgeted 434,800 oil changes, averaging 12 minutes each. Standard variable labor and support costs per oil change were as follows Direct oil specialist services: 12 minutes at $23 per hour Variable support staff and overhead: 12.0 minutes at $17 per hour $4.60 3.4 . Fixed overhead costs Annual budget $1,038,800 Fixed overhead is applied at the rate of $3.80 per oil change. Actual oil change costs: S4,260,620 1,573,152 1,410,000 Direct oil specialist services: 468,200 changes averaging 21 minutes at $26 per hour Variable support staff and overhead: 0.21 labor-hours at $16 per hour x 468,200 changes Fixed overhead Required: a. Prepare a cost vanance analysis for each variable cost or last year. If there is no effect, do not select either option.) Do not round intermediate calculations. ndicate the effect o each variance b selectin forta ora le or ? ruina rable Efficiency Variance Total Variance Oil specialist Variable overhead