A closed cylindrical tank contains 36 (pie) cubic feet of water and is filled to half its capacity. When the tank is placed upright on its circular base on level ground, the height of the water in the tank is 4 feet. When the tank is placed on its side on level ground, what is the height, in feet, of the surface of the water above the ground?
The answer is 3… *Please explain HOW you get this answer. Extra points for detail.