cm . Find the ratio of heights. . If the ratio of radii of two spheres is : , find the ratio of their volumes.
. A solid sphere and a solid hemisphere have equal total surface area. Prove that the ratio of their volume is : . The outer and the inner surface areas of a spherical copper shell are p cm and p cm respectively.
Find the volume of the material required to make the shell. . A container open at the top is in the form of a frustum of a cone of height cm with radii of its lower and upper ends are cm and cm respectively. Find the cost of milk which can completely fill a container at the rate of ` per litre.