We are asked to solve for the index of refraction and the formula is n = c/v where "n" represents the index of refraction, "c" represents the speed of light in the vacuum while "v" represents the speed of another medium.
In the problem, we have the given values below:
c = 3 x 10^8 m/s
v = 2 x 10^8 m/s
n =?
Solving for n, we have the solution below:
n = 3x10^8 / 2x10^8
n = 1.5
The answer is 1.5 for the index of refraction.