Two small spherical metal balls, having equal masses, are made from materials of densities ${\rho }_1$ and ${\rho }_2\left({\rho }_1=8{\rho }_2\right)$ and have radii of 1mm and 2mm, respectively. They are made to fall vertically (from rest) in a viscous medium whose coefficient of viscosity equals $\eta$ and whose density is $0.12{\rho }_2.$ The ratio of their terminal velocities would be