Correct answer: 1.414
For a prism at minimum deviation, the refractive index is given by \(n=\sin\left(\frac{A+D_m}{2}\right)/\sin\left(\frac{A}{2}\right)\). Substituting \(A=60^\circ\) and \(D_m=30^\circ\) gives \(n=\sin 45^\circ/\sin 30^\circ=\frac{\sqrt2/2}{1/2}=\sqrt2\approx1.414\).