Question

the radii of two circles are in the ratio 2:3 what is the radii of the circumference

Answer 1

Let the radius to be 2y and 3y
$circumference \: = 2\pi \: \times radius \\ reqd \: ratio \: = \frac{2\pi \times 2y}{2\pi \times 3y} \\ = \frac{2}{3}$
Ratio of circumferences is 2:3