Question

if two circles have circumference of 12 pi inches and 18 pi inches,find the ratio between their radii

Answer 1

The formula for the circumference is:
$2\pi r$
So to find first radius:
$2\pi r = 12\pi \\ \\ \pi r = 6\pi \\ \\ r = 6$
Second radius:
$2\pi r = 18\pi \\ \\ \pi r = 9\pi \\ \\ r = 9$
The ratio between them is:
$\frac{6}{9} = \frac{2}{3} = 0.66667$