Windsor Floors produces a variety of tiles used for kitchen flooring. Two of Windsor Floors lines are particularly popular with local home builders. The standard grade is a 6-inch (15 cm) square, high-glass tile. The high grade is an 8-inch (20 cm) square tile with a rough sandstone finish. When the housing market gets tight, home builders use more of the standard grade to keep the overall cost of the house lower. The following information is available for sales during the last six-month period.

Standard ContributionActual ContributionStandard PriceMarginStandard VolumeActual PriceMarginActual Volume6-inch$23/case$10.50231,000$21/case$7.00207,9008-inch$60/case$30.0046,200$56/case$27.0060,060

Calculate the contribution margin sales mix variance.