San Francisco Corporation uses two materials in the production of its product. The materials, X and Y, have the following standards:

Material	Standard Mix		Standard Unit Price		Standard Cost
X	3,500 units		$1.00 per unit		$3,500
Y	1,500 units		3.00 per unit		$4,500
Yield	4,000 units

During April, the following actual production information was provided:

Material	Actual Mix
X	30,000 units
Y	20,000 units
Yield	36,000 units

What is the materials mix variance?

a.$5,000 (F)

b.$10,000 (F)

c.$15,000 (F)

d.$10,000 (U)