Let radius of first cylinder is r and that of other is R and their height is h.
so vol.of first cylinder×36
=vol.of second cylinder
36×pi×r^2×h=pi×R^2×h
now pi and h cancel on both sides
so r^2×36=R^2
Squareroot36r^2=R
6r=R
so radius of second cylinder = 6 times radius of first cylinder