The power required to crush 100 ton/hr of a material is 179.8kW, if 80% of the feed passes through a 51mm screen and 80% of the product passes through a 3.2mm screen. What is the work index of the material? What will be the power required for the same feed at 100 ton/hr to be crushed to a product such that 80% is to pass through a 1.6mm screen? [10]