An organic compound undergoes first order decomposition. The time taken for the decomposition to 1/4 and 1/10 of its initial concentration are  $t_{1/4}$ and  $t_{1/10}$  respectively. What is the value of  $\frac{\left[t_{1/4}\right]}{\left[t_{1/10}\right]}\times 20?$ (take  ${{\log }_{10}}^2=0.3$)