A metal cylinder of base 5 cm and height 12 cm is melted to make n solid cones of height 1 cm and base radius 1 mm. What is the value of n?

The volume of the cylinder must be equal to the volume of n cones Volume of the cylinder V = pi x 5^2 x 12 Volume of n cones V = n x (pi x 0,1^2 x 1)/ 3 Then, pi x 25 x 12 = n x (pi x 0,01 x 1)/3 n = 90000 cones

5 solid spheres of radius 2 m, 7 solid cylinder of radius 3 m, height 7 meter and 4 solid cones of radius 5 m, height 8 m are melted to form a bigger solid sphere. What is the radius of this bigger solid sphere in meters?

11 solid spheres of radius 3 m, 9 solid cylinder of radius 4 m, height 5 meter and 13 solid cones of radius 2 m, height 4 m are melted to form a bigger solid sphere. What is the radius of this bigger solid sphere in meters?

2 solid spheres of radius 3 m, 3 solid cylinder of radius 2 m, height 3 meter and 2 solid cones of radius 2 m, height 4 m are melted to form a bigger solid sphere. What is the radius of this bigger solid sphere in meters?

A cylinder of base radius r and height h is dipped vertically to half the height in a bucket full of purple paint. Find the area of the surface which get painted?