A container has two chambers of volumes$V_1$= 2 litres and $V_2$ = 3 litres separated by a partition made of a thermal insulator. The chambers contain$n_1$ = 5 and $n_2$ = 4 moles of ideal gas at pressures $P_1$ = 1 atm and $P_2$ = 2 atm, respectively. When the partition is removed, the mixture attains an equilibrium pressure of