Answer
$\nu_1=13.8\ ft/s$
$\dot{m}=35.1\ lbm/min$
Work Step by Step
$\nu_1=\frac{\dot{V}_1}{A_1}=\frac{4\dot{V}_1}{\pi D^2}$
With $\dot{V}_1=450\ ft³/min,\ D=10\ in$:
$\nu_1=13.8\ ft/s$
$\dot{m}=\rho_1\dot{V}_1$
With $\rho_1=0.078\ lbm/ft³$
$\dot{m}=35.1\ lbm/min$
