A solid metal cylinder of radius 12 cm and height of 18 cm is melted and cast into spheres of 3 cm radius. The number of spheres that can be made is

16) The shadow of Qutub Minar is 80 m long. When the angle of elevation of the sun is 45 degree, then the height of Qutub Minar is

17) The tempering temperature for high speed steel is

18) In flame hardening steel products are constantly heat till

19) In second-order lever