Ch. 9 - The Keurig Company manufactures single cup/single serving coffee makers for global distribution. The company uses a single cost function represented as: Y-a + bx, for estimating production costs Keurig estimates that fixed production costs will be $3,700 per month plus $9 per unit. For the month of December, Keurig planned for activity of 1000 units, but the actual level of activity was 900 units. The actual maintenance cost for the month was $12,000. The activity variance for production costs for the month of December would be closest to: $700 U $700 F $900 F $900 U