Nice Area Problem (2)

Geometry Level 2

This target has five colors and each color is divided into two parts for scoring zones.

All 9 rings have the same width as the radius of the innermost circle.

What is the ratio of the white area to the yellow area?

6 7 8 9 10

1 solution

Blan Morrison
May 10, 2018

Assume that the radius of the innermost circle is 1. Let $A_1=\text{the area of the yellow section}$ and $A_2=\text{the area of the white region}$ .

$A_1=2^2\pi=4\pi$ $A_2=10^2\pi - 8^2\pi=36\pi$ $\frac{A_2}{A_1}=\frac{36\pi}{4\pi}=\frac{36}{4}=\boxed{9}$