Swifty Company has a materials price standard of $2.40 per kilogram. 3920 kilograms of materials were purchased at $2.10 a kilogram. The actual quantity of materials used was 3590 kilograms, although the standard quantity allowed for the output was 3490 kilograms. Swifty Company's total materials variance is

$9360 U. $8324 U. $100 F. $936 F.