A solid is in the form of a cone standing on a hemisphere with both their radii being equal to 8 cm and the height of cone is equal to its radius. Find in terms of π, the volume of the solid.

The diameter of a sphere is 6 cm. It is melted and drawn into a wire of diameter 0.2 cm. Find the length of wire.

The cross-section of a tunnel is a square of side 7 m surmounted by a semicircle as shown in the adjoining figure. The tunnel is 80 m long. Calculate:

(i) its volume,

(ii) the surface area of the tunnel (excluding the floor) and

(iii) its floor area.