$4\mathrm{.}23$ WP Helium gas flows through a well$-$insulated nozzle at steady state. The temperature and

velocity at the inlet are $550R$ and $150f\frac{t}{s},$ respectively. At the exit, the temperature is $400R$ and

the pressure is $40lb\frac{f}{i}n.{?}^2$ The area of the exit is $0\mathrm{.}0085f{t}^2.$ Using the ideal gas model with $k=$

$1\mathrm{.}67,$ and neglecting potential energy effects, determine the mass flow rate, in $l\frac{b}{s},$ through the

nozzle.