Wave Optics

A ray of light of intensity ' I ' is incident on a parallel glass slab at a point ' $A$ ' as shown in figure. It undergoes partial reflection and refraction. At each reflection $25 \%$ of incident energy is reflected. The rays $A B$ and $A B$ undergo interference. The ratio $\frac{\mathrm{I}_{\text {max }}}{\mathrm{I}_{\text {min }}}$ is