A system consists of two types of gas molecules $A$ and $B$ having same number density $2 \times 10^{25} / \mathrm{m}^3$. The diameter of $A$ and $B$ are 10 A and 5 A respectively. They suffer collision at room temperature. The ratio of average distance covered by the molecule $A$ to that of $B$ between two successive collision is $\_\_\_\_$ $\times 10^{-2}$