Correct answer: 1.6
The apparent shift due to refraction is given by the formula: shift = t(1 - 1/μ), where t is the thickness of the glass and μ is the refractive index. The total distance between the object and the image is 8 cm (object distance) + 6 cm (thickness of glass) + 12 cm (distance behind the silvered face) = 26 cm. The apparent distance through the glass is 6/μ. Solving for μ using the given distances, we find μ = 1.6.