a cylindrical tank with height 15 m and diameter 2 m i being filled with gasoline at a rate of 0.5 m^3/min. At what rate is the fluid level in the tank rising? About how long will it take to fill the tank?

Just not sure about the second part of the question regarding how long it would take to fill the tank. dh/dt ended up being 1/(2pi) m/min and so would it just be 15/ (1/2pi) = t?