The velocity profile for a fully developed laminar flow of an incompressible Newtonian fluid, at steady state, through a horizontal infinitely wide and long slit of gap $0.01 ~\text{m}$ is given by the following equation.
\[
u(y)=7.5-3 \times 10^{5} y^{2}
\]
where $y$ is the vertical distance measured from the center of the slit. The average velocity of the fluid (in $\mathrm{m} \mathrm{s}^{-1}$ ) is $\_\_\_\_$ (rounded off to the nearest integer).
