The cylindrical tank radius is
m.
Tank is being filled with water at a rate of
m3/min.
Therefore rate of increase of volume
.
The volume of the cylinder is
.
where
is height of the cylinder.
.
Differentiate on each side with respect to
.

Substitute
and
in above expression.

Height of the water increases at rate of
m/min.
\
The height of water is increasing at a rate of
m/min.