A saturated liquid feed containing $35$mok$\%x(1),35$ mole $\%Y(2)$ and $30$ mole $Z(3)$ is to be fractioned to recover $97\%$ of the $x$ at the top and $98\%$ of the $Y$ in the bottom product. The total pressure is essentially atmospheric and the reflux returnet the tower is at its bubble point. Determinea minimum number of trays and minimum reflux ratio.

$Z$ does not come out the top.

t Take the basis as Feed $=1000$kmo$\frac{l}{h}$

The average relative volatility ${}_{12}=2\mathrm{.}4,{}_{32}=0\mathrm{.}45$