Question

A Susan B. Anthony dollar coin has a diameter of 26.50 millimeters. What is the area of the coin to the nearest hundredth?

Answer 1

`551.55 mm^2`

Explanation:

Coin's diameter is 26.50 millimetres

using the unit of measurement of `mm` for millimetres

So its radius is `1/2xx26.50 = 13.25mm`

Area of a circle is `pixx("radius")xx("radius") -> pi("radius")^2`

So the area is `pixx13.25xx13.25`

Using a calculator this is: 551.54586....

For the nearest hundredth we have the cut off point:

`551.54color(red)(|)586...`
`" "color(red)(uarr)`
`color(red)("cut off point")`

The digit immediately to the right of the cut of point is classified as 5 or more. So the digit to the left of the cut off point is raised by 1 and all those to the right made into 0

`551.55color(red)(|)000..`
`" "color(red)(uarr)`
`color(red)("The 4 changed to 5")`