Refraction consists in the bending of light or the change in its direction when passing through a medium with a refractive index [tex]n[/tex] different from the other medium.
Being its equation as follows:
[tex]n=\frac{c}{v}[/tex]
Where [tex]c[/tex] is the speed of light in vacuum and [tex]v[/tex] its speed in the other medium.
Now, writing this equation with the known values, we will have Z's index of refraction:
[tex]n=\frac{3(10)^{8} m/s}{2.5(10)^{8} m/s}[/tex]
[tex]n=1.2[/tex]
