Question

Find the volume and surface area of a sphere of radius 21 cm. (Use pi = 22/7.)

Solution

1. Volume = 4/3 x pi x r^3 = 4/3 x (22/7) x 21 x 21 x 21.
2. 21 x 21 x 21 = 9,261, and 9,261 / 7 = 1,323, so the volume = 4/3 x 22 x 1,323 = 4 x 22 x 441 = 38,808 cm^3.
3. Surface area = 4 x pi x r^2 = 4 x (22/7) x 441 = 4 x 22 x 63 = 5,544 cm^2.
4. The volume is 38,808 cm^3 and the surface area is 5,544 cm^2.