Wave Optics

In Young's double slit experiment, waves from slits ' $\mathrm{S}_1$ ' and ' $\mathrm{S}_2$ ' have a path difference of $\frac{\lambda}{4}$ and $\frac{\lambda}{6}$ respectively at points $x$ and $y$ on the screen. The ratio of intensities at points $y$ to that at $x$ is $\left(\cos 45^{\circ}=\frac{1}{\sqrt{2}}, \cos 30^{\circ}=\sqrt{3} / 2,\right)$