**We have,**

Ratio of their height = 1:2

Height of cylinder 1 = h_{1}

Height of cylinder 2 = h_{2}

h_{1} / h_{2} = 1/2

**Volume of cylinder 1, V**_{1} = volume of cylinder 2, V_{2}

V_{1} = V_{2}

πr_{1}^{2}h_{1} = πr_{2}^{2}h_{2}

r_{1}^{2} / r_{2}^{2} = 2/1

r_{1} / r_{2} = √(2/1)

= √2 / 1

**∴ Ratio of their radii is √2:1**