Consider the two different first order reactions given below

$\begin{aligned} & \mathrm{A}+\mathrm{B} \rightarrow \mathrm{C} \text { (Reaction 1) } \\ & \mathrm{P} \rightarrow \mathrm{Q} \text { (Reaction 2) } \end{aligned}$

The ratio of the half life of Reaction 1 : Reaction 2 is $5: 2$ If $t_1$ and $t_2$ represent the time taken to complete $2 / 3^{\text {rd }}$ and $4 / 5^{\text {th }}$ of Reaction 1 and Reaction 2 , respectively, then the value of the ratio $t_1: t_2$ is _________ $\times 10^{-1}$ (nearest integer). [Given : $\log _{10}(3)=0.477$ and $\log _{10}(5)=0.699$]