The immiscible liquids of densities $d_1 > d_2 > d_3$ and refractive indices $\mu_1 > \mu_2 > \mu_3$ are put in a beaker . The height of each liquid column is $\large\frac{h}{3}$. A dot is made at the bottom of the beaker . For near normal vision, find the apparent depth of the dot .

Question

$\begin{array}{1 1} 3h [ \mu_1 +\mu_2 + \mu_3] \\ \frac{3}{h} [ \mu_1 +\mu_2 + \mu_3] \\ \frac{h}{3} [ \frac{1}{\mu_1} +\frac{1}{\mu_2} + \frac{1}{\mu_3}] \\ \frac{h}{3} [ \mu_1 +\mu_2 + \mu_3] \end{array}$