A heap of wheat is in the form of a cone whose diameter is 10.5 m and height is 3 m. Find its volume. The heap is to be covered by canvas to protect it from rain. Find the area of the canvas required.

Find the volume of a sphere whose radius is 7 cm.

Find the amount of water displaced by a solid spherical ball of diameter 28 cm.

Find the amount of water displaced by a solid spherical ball of diameter 0.21 m.