A sample of milk splits after 60 min. at 300 K and after 40 min. at 400 K when the population of lactobacillus acidophilus in it doubles. The…

A sample of milk splits after $\displaystyle 60$ min . at $\displaystyle 300$ K and after $\displaystyle 40$ min . at $\displaystyle 400$ K when the population of lactobacillus acidophilus in it doubles. The activation energy (in $\displaystyle \mathrm{kJ} / \mathrm{mol}$ ) for this process is closest to \_\_\_\_. (Given, $\displaystyle \mathrm{R}=8.3 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}, \ln \left(\frac{2}{3}\right)=0.4$, $\displaystyle \left.e^{-3}=4.0\right)$