A solution of iodoethane, I, and propanone, P, with a mole. fraction of $I, x_{1}=0.55$, had a partial vapour pressure of $I$ of $28.44 \mathrm{kPa}$ and a partial vapour pressure of $\mathrm{P}$ of $19.21 \mathrm{kPa}$ at $50^{\circ} \mathrm{C}$. At this temperature, the saturated vapour pressure of I is $47.12 \mathrm{kPa}$ and of $\mathrm{P}$ is $37.38 \mathrm{kPa}$. Calculate the activity coefficients of both components in the solution. (Section 17.4)