The ratio of the radii of two circle is 3 : 2. What is the ratio of their circumferences ?

Answer: Option B

Let the radii of the two circle be 3r and 2r respectively
Then, required ratio :
$$\begin{array}{rl}& =\frac{2\pi \left(3r\right)}{2\pi \left(2r\right)}\\ & =\frac{3}{2}\\ & =3:2\end{array}$$