#### Answer

4:1

#### Work Step by Step

The ratio of the circumferences of two circles is 2:1. We need to find the ratio of their areas
Let us assume the circle radius of the first one is r1
and the second one is r2
The circumference ratios is 2$\pi$r1 : 2$\pi$r2 = 2:1
r1 : r2 = 2:1
Let us assume r1 = 2x and r2 = x
The area A of a circle whose radius has length r is given by
A = $\pi r^{2}$
Therefore A1 : A2 = $\pi r1^{2}$ :$\pi r2^{2}$
$r1^{2}$ : $r2^{2}$
$(2x)^{2}$ : $(x)^{2}$
4$x^{2}$ : $(x)^{2}$
A1:A2 = 4:1