Three samples of the same gas, x y and z, for which the ratio of specific heats is $\gamma =3/2,$ have initially the same volume. The volume of the each sample is doubled by adiabatic process in the case of x, by isobaric process in the case of y and by isothermal process in the case of z. If the initial pressure of the sample of x, y and z are in the ratio $2\sqrt{2}:1:2$; then the ratio of their final pressures is