A glass convex lens of refractive index $\large\frac{3}{2}$ has got a focal length equal to $50 \;cm$ Find the focal length of lens if it is immersed in ethyl alcohol of $refractive index \;1.36$

Question

$(a)\;142.75 \;cm \\ (b)\;262.75\;cm \\ (c)\;382.75\;cm \\ (d)\;242.75\;cm$