What will be the height of the surface of the water above the ground?
A cylindrical closed tank contains 36p cubic metres of water, and is filled to half of its capacity. When the cylindrical tank is placed upright on its circular base on level ground, the height of the water in the tank is 4 metres. But when this tank is placed on its side on level ground, what will be the height of the surface of the water above the ground?
(a) 9 metres
(b) 6 metres
(c) 3 metres
(d) 1 metres