Let $\eta_1$ is the efficiency of an engine at $T_1=447^{\circ} \mathrm{C}$ and $T_2=147^{\circ} \mathrm{C}$ while $\eta_2$ is the efficiency at $T_1=947^{\circ} \mathrm{C}$ and $\mathrm{T}_2=47^{\circ} \mathrm{C}$. The ratio $\frac{\eta_1}{\eta_2}$ will be
