${\mathrm{ϵ}}_0$ and ${\mathrm{\mu }}_{\mathrm{o}}$ are the electric permittivity and magnetic permeability of free space respectively. If the corresponding quantities of a medium are 2${\mathrm{ϵ}}_0$ and 1.5${\mathrm{\mu }}_{\mathrm{o}}$ respectively, the refractive index of the medium will nearly be :