If the radius of the base of a right circular cone is 3r and its height is equal to the radius of the base, then its volume is

The slant height of a cone is increased by 10%. If the radius remains the same, the curved surface area is increases by

The height of a solid cone is 12 cm and the area of the circular base is 64π cm². A plane parallel to the base of the cone cuts through the cone 9 cm above the vertex of the cone, the area of the base of the new cone so formed is

If the volume of two cones are in the ratio 1 : 4 and their diameters are in the ratio 4 : 5, then the ratio of their heights, is

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