What is the index of refraction of a material in which the speed of light is 1.69 × 108 m/s?

The index of refraction is essentially the speed of light through a vacuum (extremely similar to air) divided by the speed of light through given medium.
I also attached a copy of my physics notes on refraction and that sort of jazz as they may be helpful :)
Hopefully I helped :D

1. Type of Material

2. Charge of an object

3. movement of an object

4. Presence of an electric field

Hope this helps uwu <3