ANSWER:
[tex]2.29\cdot10^8\text{ m/s}[/tex]STEP-BY-STEP EXPLANATION:
Light in a vacuum has the following speed
[tex]s=3\cdot10^8\text{ m/s}[/tex]Now, the speed of light through a material is equal to the speed in vacuum divided by the index of refraction. Therefore:
[tex]s_{\text{ice}}=\frac{3\cdot10^8}{1.31}=2.29\cdot10^8\text{ m/s}[/tex]