Dubberly Corporation's cost formula for its manufacturing overhead is $30,900 per month plus $64 per machine-hour. For the month of March, the company planned for activity of 7,960 machine-hours, but the actual level of activity was 7,910 machine-hours. The actual manufacturing overhead for the month was $563,110. Dubberly Corporation's cost formula for its manufacturing overhead is $30,900 per month plus $64 per machine-hour. For the month of March, the company planned for activity of 7,960 machine-hours, but the actual level of activity was 7,910 machine-hours. The actual manufacturing overhead for the month was $563,110. The activity variance for manufacturing overhead in March would be closest to: Multiple Choice $22,770 U $22,770 F $3,200 F $3,200 U