Consider the two different first order reactions given below (A+B...

Consider the two different first order reactions given below (\mathrm{A}+\mathrm{B} \rightarrow \mathrm{C}) (Reaction 1$)$ (P \rightarrow Q) (Reaction 2) 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 (45^{\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)]