A double convex lens has focal length $25 \mathrm{~cm}$. The radius of curvature of one of the surfaces is double of the other. Find the radii if the refractive index of the material of the lens is 1.5. (1) $50 \mathrm{~cm}, 100 \mathrm{~cm}$ (2) $100 \mathrm{~cm}, 50 \mathrm{~cm}$ (3) $25 \mathrm{~cm}, 50 \mathrm{~cm}$ (4) $18.75 \mathrm{~cm}, 37.5 \mathrm{~cm}$