# Video: Finding the Volume of a Sphere in a Real-Life Context

A tennis ball has a diameter of 6.7 cm. Work out the volume of four such tennis balls, giving your answer to the nearest cubic centimeter.

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### Video Transcript

A tennis ball has a diameter of 6.7 centimeters. Work out the volume of four such tennis balls, giving your answer to the nearest cubic centimeter.

We know that the volume of any sphere is four-thirds 𝜋𝑟 cubed, where 𝑟 is the radius of the sphere. In this question, we’re told that the diameter of one tennis ball is 6.7 centimeters. The radius of a sphere is half its diameter, so we can calculate the radius by dividing 6.7 by two. This is equal to 3.35 centimeters. The volume of one tennis ball is therefore equal to four-thirds multiplied by 𝜋 multiplied by 3.35 cubed. This is equal to 157.479 and so on.

As we need to calculate the volume of four tennis balls, we need to multiply this number by four. This is equal to 629.916 and so on. As we need to round our answer to the nearest cubic centimeter, the deciding number is the nine in the tenths column. If our deciding number is five or greater, we round up.

The volume of four tennis balls with diameter 6.7 centimeters is 630 cubic centimeters to the nearest cubic centimeter.