If a parabolic reflector is 20 cm in diameter and 50 cm deep. Find the focus.

If a parabolic reflector is 20 cm in diameter and 5 cm deep, find the focus.

A cylindrical pillar is 50 cm in diameter and 3.5 m in height. Find the cost of painting the curved surface of the pillar at the rate of ₹ 12.50 per m^2 .Assume pi = 22/7 , unless stated otherwise.

A cylinderical pillar is 50 cm in diameter and 3.5 m in height. Find the cost of white washing the curved surface of the pillar at the rate of Rs 12.50 per m^2 .

The outer diameter of a spheircal shell is 10 cm and the inner diameter is 9 cm. find the volume of the metal contained in the shell.

A metal pipe is 77 cm long. The inner diameter of a cross section is 4 cm, the outer diameter being 4.4 cm. Find outer curved surface area.

A metal pipe is 77 cm long. The inner diameter of a cross section is 4 cm, the outer diameter being 4.4 cm. Find total surface area.