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

1 Answer
Tony B
Jan 27, 2017

#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")#

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