A double convex thin glass lens has equal radii of curvature. The focal length of the lens is +81.1 centimeter and the index of refraction of the glass is 1.52. The lens is replaced with a Plano-convex glass lens of the same focal length and thickness. The radius of curvature of the convex surface is 13 centimeter. Find the index of refraction of the glass of the Plano-convex lens?