Two masses $M_1$ and $M_2$ are tied together at the two ends of a light inextensible string that passes over a frictionless pulley. When the mass $\mathrm{M}_2$ is twice that of $\mathrm{M}_1$. the acceleration of the system is $\mathrm{a}_1$. When the mass $M_2$ is thrice that of $M_1$. The acceleration of The system is $a_2$. The ratio $\frac{a_1}{a_2}$ will be: