$\mathrm{P}_{\mathrm{i}}=\mathrm{P} \quad \mathrm{P}_{\mathrm{f}}=4 \mathrm{P}$
By gas equation we know: $-V=\frac{n R T}{P}$
$\therefore \mathrm{PV}^{4 / 3}=\mathrm{constant}$
$\Rightarrow P\left(\frac{n R T}{P}\right)^{\frac{4}{3}}=$ constant
$\Rightarrow \frac{T^{\frac{4}{3}}}{p^{\frac{1}{3}}}=$ constant
$\therefore T_{f}=\left(\frac{P_{t}}{P_{i}}\right)^{\frac{4}{3}-\frac{4}{3}} \times T_{i}=\left(\frac{4 P}{P}\right)^{\frac{1}{4}} \times 300 \mathrm{K}$
$\Rightarrow T_{f}=300 \sqrt{2} \mathrm{K}$

Step $1$ It is first compressed adiabatically from volume $8.0 \,m ^{3}$ to $1.0 \,m ^{3}$.
Step $2$ Then expanded isothermally at temperature $T_{1}$ to volume $10.0 \,m ^{3}$.
Step $3$ Then expanded adiabatically to volume $80.0 \,m ^{3}$.
Step $4$ Then compressed isothermally at temperature $T_{2}$ to volume $8.0 \,m ^{3}$.
Then, $T_{1} / T_{2}$ is
