A feed of gypsum of which 80% of material is passed through a 20 mm screen is crushed to a product. The 80% product is passed through a 5 mm screen. If the power required is 75 kW what is the capacity of the crushing unit. When the same material is used to crush in a unit of 100 ton/hr from feed size 30 mm to 10 mm the power required is 200 kW.