A C$-$D nozzle has an exit area $2\mathrm{.}5$ time the throat area. For a steady, isentropic flow $($gamma$=1\mathrm{.}4)$ discharging into an atmosphere with pressure Pa$,$ find the Mach number at the throat and at the exit plane for:

a$.$ Pa$/$Pt$=0\mathrm{.}06$

b$.$ Pa$/$Pt$=0\mathrm{.}9725$