Dubberly Corporation's cost formula for its manufacturing overhead is $31,200 per month plus $51 per machine-hour. For the month of March, the company planned for activity of 8,020 machine-hours, but the actual level of activity was 7,940 machine-hours. The actual manufacturing overhead for the month was $463,350.The activity variance for manufacturing overhead in March would be closest to:

A) $23,130 U
B) $23,130 F
C) $4,080 F
D) $4,080 U

First, we need to calculate the budgeted manufacturing overhead for the month of March based on the cost formula provided:

$31,200 + ($51 per machine-hour × 8,020 machine-hours) = $416,820

Next, we can calculate the flexible budget amount based on the actual level of activity:

$31,200 + ($51 per machine-hour × 7,940 machine-hours) = $407,140

Finally, we can calculate the activity variance by subtracting the flexible budget amount from the actual manufacturing overhead:

$463,350 - $407,140 = $56,210 F

Therefore, the activity variance for manufacturing overhead in March would be $56,210 F.

However, the question is asking for the activity variance, which is the difference between the actual level of activity and the budgeted level of activity, not the flexible budget amount. To calculate the activity variance, we can use the following formula:

Activity Variance = (Actual Level of Activity - Budgeted Level of Activity) × Variable Overhead Rate Per Unit

Activity Variance = (7,940 machine-hours - 8,020 machine-hours) × $51 per machine-hour

Activity Variance = -$4,080 F

Therefore, the closest answer choice is C) $4,080 F.