Math CentralQuandaries & Queries


Question from Robert, a student:

A dart board consists of concetric circles and line segment. the radius of the bull's eye is 4 inches and each ring surrounding the bull's eye is 3 inches wide.
a) what is the area of the bull's eye
b) what percent is the bull's eye.

hint there are 4 rings and the bull's eye is divided into 4 (90) degree angles (meaning 1/2 up and down) (1/2 left to right.

Hi Robert.

For part (a), you know the radius of the bull's eye, and want to know the area. What formula do you have that has an A for area and an r for radius? Use that.

For part (b), you need to do three steps. First, find the radius of the whole board. Add the bull's eye's radius and the extra amount for each ring. Second, calculate the area of the whole board, using the same
formula you used in part (a). Last, find out what percentage the area of the bull's eye is (answer to part a) of the whole board's area.

Hope this helps,
Stephen La Rocque

About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS