Abbott has a standard variable overhead rate of $4.80 per machine hour, and each unit produced has a standard time allowed of 3.20 hours. The company's static budget was based on 46,000 units. Actual results for the year follow.

Actual units produced: 49,000

Actual machine hours worked: 150,000

Actual variable overhead incurred: $690,000

Abbott's variable-overhead EFFICIENCY variance is:

$30,000 favorable.

$-32,640 unfavorable.

$32,640 favorable.

$-30,000 unfavorable.

None of these.