Answer : $2 : 3$
Explanation :
$\large\frac{\bigtriangleup Q}{\bigtriangleup t}=\large\frac{KA}{l}\;\bigtriangleup T$
$t \propto \large\frac{l}{k} \quad \;(for\; \bigtriangleup T and\; A\; same)$
$\large\frac{t_{1}}{t_{2}}=\large\frac{l_{1}}{l_{2}} . \large\frac{k_{2}}{k_{1}}=\large\frac{1}{2} \times \large\frac{4}{3}=\large\frac{2}{3}$