Question

Sam drew a circle with a diameter of 16 cm. Kevin drew a circle with a radius of 6 cm. Approximately how much larger is the area of Sam's circle than the area of Kevin's circle? Use 3.14 for Pi and round to the nearest whole number

Answer 1

About 173 square centimeters larger.

Explanation:

Let's find the areas of the two, then subtract them to get our answer! Remember diameter is double radius, so Sam's circle radius = 8 cm, Kevin's circle radius = 3 cm.

Sam's circle:

A = πr^2

= π8^2

= 64π = about 200.96 square centimeters

Kevin's circle:

A = πr^2

= π3^2

= 9π = 28.26 square centimeters.

200.96 - 28.26 = 172.7 = about 173 square centimeters larger

*Remember: we round at the end, not after each step.*

Answer 2

88 cm squared

Explanation:

Sam's circle has a radius of 16/2=8 cm.
`\pi\cdot 8^2=200.96`

For Kevin,
`\pi\cdot 6^2=113.04`

The difference between these is 87.92 squared cm. Rounded to the nearest whole number, this is 88.