A manufacturing company ships its product in two different sizes of truck trailers. Each shipment is made in a trailer with dimensions 8xfeetx10xfeetx30xfeet or 8xfeetx10xfeetx40xfeet. If 30x1% of its shipments are made by using 30-foot trailers and 70x% by using 40-foot trailers, find the mean volume shipped per trailer load. (Assume that the trailers are always full.)