Finding exit resistance of a MOSFET
With the provided information it is not possible to calculate the output resistance \$r_{ds}\$.

However, since $$r_{ds} \approx \frac{1}{\lambda I_d}$$ 
and $$\lambda = \frac{1}{V_E} \frac{\Delta L} L$$

it is possible to determine that
$$ \frac{r_{ds1}}{r_{ds2}} = \frac{\lambda_2}{\lambda_1} = \frac {L_1}{L_2} = 2$$