Question

Three tennis balls are just packed in a cylindrical jar. If radius of each ball is r, volume of air inside the jar is

Options

• 2πr³

• 3πr³

• 5πr³

• 4πr³ 

Answer 1

2πr³ 

Explanation:

Radius of cylinder = Radius of ball = r.

Height of cylinder (h) = 3 × Diameter of ball

= 3 × (2r)

 = 6r

Volume of cylinder = πr²h

= π × r² × 6r

= 6πr³

Volume of 3 balls = `3 xx 4/3 πr^3`

= 4πr³

Volume of air = Volume of cylinder – Volume of 3 balls

= 6πr³ – 4πr³

= 2πr³

The volume of air inside the jar is 2πr³.