Triton Mfg. uses standard costing for its product costing. Manufacturing overhead is applied based on standard direct labour hours (DLH). Overhead cost information is presented below:

	Input	Cost per unit
Variable	$7.20 per DLH	36
Fixed	$9.60 per DLH	48
Total		$ 84

During the most recent month a total of 7,800 units were produced; 40,100 DLH were used and total actual manufacturing overhead was $720,000 of which $391,000 was fixed. What was the variable overhead efficiency variance?

a.$7,920 F

b.$7,920 U

c.$40,280 F

$40,280 U