A cylinder with adiabatic walls is closed at both ends and is divided into two compartments by a frictionless adiabatic piston. Ideal gas is filled…

A cylinder with adiabatic walls is closed at both ends and is divided into two compartments by a frictionless adiabatic piston. Ideal gas is filled in both (left and right) the compartments at same $\displaystyle P, V$, $\displaystyle T$. Heating is started from left side until pressure changes to $\displaystyle 27 P / 8$. If initial volume of each compartment was $\displaystyle 9$ litres then the final volume in right-hand side compartment is $\displaystyle \_\_\_\_$ litres. (for this ideal gas $\displaystyle \mathrm{C}_{\mathrm{P}} / \mathrm{C}_{\mathrm{V}}=1.5$ )