A thin glass plate of thickness is (2500)/(3) λ ( λ is wavelength...

A thin glass plate of thickness is $\frac{2500}{3} \lambda$ ( $\lambda$ is wavelength of light used) and refractive index $\mu=1.5$ is inserted between one of the slits and the screen in Young's double slit experiment. At a point on the screen equidistant from the slits, the ratio of the intensities before and after the introduction of the glass plate is :