[tex]n = \frac{sin(i)}{sin(r)} [/tex]
[tex]1.50 = \frac{sin(30)}{sin(r)} \\ 1.50 = \frac{0.5}{sin(r)} \\ sin(r) = \frac{0.5}{1.5} \\ sin(r) = 0.3333[/tex]