n = \(\frac{\frac{A+D}{2}}{sin\frac{A}{2}}\)

where A = the refracting angle of the prism(60º)
D = angle of deviation of the ray (30°)

n = \(\frac{\frac{60+30}{2}}{sin\frac{60}{2}}\)

= \(\frac{sin45}{sin30}\)

v = \(\frac{\frac{1}{\sqrt{2}}}{\frac{1}{2}}\)
 \(\frac{\frac{\sqrt{2}}{2}}{\frac{1}{2}}\)
=  \(\frac{\sqrt{2}}{2}\) x \(\frac{2}{1}\) = \(\sqrt{2}\)
n = \(\sqrt{2}\)