Light travels at 1.9 × 10⁸ m/s in material A and at 2.4 × 10⁸ m/s in material B.

Step 1. (a) $n_A = \dfrac{3.00 \times 10^{8}\ \text{m/s}}{1.9 \times 10^{8}\ \text{m/s}} = 1.58$ and $n_B = \dfrac{3.00 \times 10^{8}\ \text{m/s}}{2.4 \times 10^{8}\ \text{m/s}} = 1.25$.

Step 2. (b) A has the larger index: A is optically denser.

Step 3. (c) From denser A into rarer B, the ray bends away from the normal.