From a right cone of height h and with base radius r a cone has been cut of from the centre of the height. The volume of remaining frustum of the cone is.

The area of the base of a right circular cone is 400π and its height is 15 cm. The curved surface of the cone ( in cm²) is:

If the areas of circular ring having inner and outer radius 8 cm and 12 cm respectively is equal to the total surface area of cylinder of radius R₁ and height h, then h in terms of R₁ will be :

The ratio between the length and breadth of a rectangular park is 3: 2. If a man cycling along the boundary of the park at the speed of 12 Km./hr. completes one round in 8 min, then the area of the park in sq.m is – 

A semicircle is folded to make a cone. Find the height (in cm) of the cone if diameter of the semicircle is 28 cm?

The area  of a circle is 616 sq cm, find its circumference?

A cylindrical well of depth 21 m with internal radius of 13 m is dug up. The mud, so detained, is spread evenly to form a platform of dimension 52 × 13.2. What is the height of the platform?

A rectangular grass plot 80 m × 60 m has two roads, each 10 m wide, running in the middle of it; one parallel to length and the other parallel to breadth. Find the cost of gravelling the roads at ₹ 2 per m².