Calculus: related rates, cone, & water level rising?

A cone of radius 10 cms and height 20 cms is lowered, vertex first, into a cylindrical tank of water with a radius of 40 cms. The vertex of the cone approaches the bottom of the tank at 1 cm per second. How fast is the water level rising in the tank when half the heigh of the cone is submerged? Please show the work for this? Thank you!