Question

A hollow ball is made of rubber that is 1 cm thick. The ball has a radius of 5 cm at the outside surface. What is the approximate volume of rubber used to make the ball? Use 3.14 to approximate pi.

255.4 cm³
267.9 cm³
523.3 cm³
2043.1 cm³

Answer 1

V=4/3(3.14)r^3
V=4/3(3.14)(5^3-(4)^3)
V=4/3(3.14)(125-64)
V=255.4cm^3(calculator)(tenth decimal place)
A

Answer 2

Option 1. 255.4 cm³

Explanation:

Since radius of the ball at the outer surface is = 5 cm³

Therefore volume of the ball formed by outer surface = (4/3)×π×5³ cm³

The ball is made up of 1 cm thick rubber so the radius of ball with inner surface = 5-1 = 4 cm

and volume of the ball formed by inner surface = (4/3)×π×4³ cm³

Now the volume of the rubber = Volume of the ball with outer layer - Volume of the ball with inner layer

V = (4/3)×π×5³ - (4/3)×π×4³ = (4/3)×π×(5³- 4³) = (4/3)×3.14×(61) = 255.38

V = 255.4 cm³

Option 1. 255.4 cm³ is the correct answer.