The breadth of a rectangular hall is three - fourth of its length. If the area of the floor is 768 sq. m., then the difference between the length and breadth of the hall is: 

The total surface area of a solid right circular cylinder is twice that of a solid sphere. If they have the same radii, the ratio of the volume of the cylinder to that of the sphere is given by

The diameter of a toy wheel is 14 cm, what is the distance travelled by it in 15 revolutions? 

If a wire is bent into the shape of a square, the area of the square is 81 sq. cm. When the wire is bent into a semicircular shape, the area of the semicircle is