A wastewater-treatment plant consists of primary treatment followed by an activated-sludge secondary system. Sludges from the primary clarifier and waste-activated sludge from the underflow are mixed and thickened in a gravity thickener. The primary sludge contains 1250 kg of dry solids per day with a 4 percent solids content. The waste-activated sludge contains 525 kg of dry solids per day and has a solids content of 1.2 percent. After thickening, the mixture has a solids content of 3.0 percent.

Calculate (a) the volume of sludge that must be processed after thickening and (b) the percent volume reduction in the thickener.