Providence Hospital generates monthly performance reports for each of its departments. The hospital must maintain an adequate staff of attending and oncall physicians at all times, so physician costs are not affected by the number of patient visits. But all other costs do vary with patient activity. Nursehours are used as the activity measure for nursing costs, and patient visits are used as the activity measure for the cost of supplies and other variable costs. The head physician of the hospital's emergency room, Volanda Mortensen, is responsible for control of costs. During October, the emergency room unit expected to treat 3,700 patients but actually treated 4,200 patients. The following additional information for October is available: Budget Actual Variance Nurse-hours 1,480 1,764 -284 Nursing costs $37,000 $33,800 $3,200 Supplies & other variable costs $40,700 $25,700 $15,000 Fixed costs $97,000 $93,500 $3,500