ABCD is a composite slab made of two slabs of transparent materials having refractive indices ${\mathrm{\mu }}_1=\raisebox{1ex}{$4$}\!\left/ \!\raisebox{-1ex}{$3$}\right.$ and ${\mathrm{\mu }}_2=\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$. P is a small object. For near normal vision from top of the composite slab, the apparent position of the object P i.e. at the interface of the slabs. Then the ratio $\frac{{\mathrm{t}}_1}{{\mathrm{t}}_2}$ is