Answer: 1.2
Refraction consists in the bending of light or the change in its direction when passing through a medium with a refractive index 
 different from the other medium.
 different from the other medium. 
Being its equation as follows:
 
 
Where 
 is the speed of light in vacuum and
 is the speed of light in vacuum and 
 its speed in the other medium.
 its speed in the other medium.
Now, writing this equation with the known values, we will have Z's index of refraction:
 
 
