Two small balls of same density \(\sigma\) and radii \(r\) and \(\frac{r}{3}\) are dropped into two different tubes of length \(L\), filled with liquids of densities \(\frac{\sigma }{2}\) and \(\frac{\sigma }{3}\) and coefficients of viscosity \(\eta _{1}\) and \(\eta _{2}\) respectively. If both balls reach the bottom of the tubes simultaneously, having moved at their respective terminal velocities, and the ratio \(\frac{\eta _{1}}{\eta _{2}}=\frac{x}{4}\), the value of \(x\) is