If the volumes of two cones be in the ratio 1 : 4. and the radii of their bases be in the ratio 4 : 5, then the ratio of their heights is

The height of a cone is 21 cm and its slant height is 28 cm. The volume of the cone is

The volume of a right circular cone of height 24 cm is 1232 cm³. Its curved surface area is

If the height of a cone is doubled, then its volume is increased by

The curved surface area of one cone is twice that of the other while the slant height of the latter is twice that of the former. The ratio of their radii is