JEE Mains 31-Jan-2023 Shift 1 Solved Paper

In a medium the speed of light wave decreases to 0.2 times to its speed in free space The ratio of relative permittivity to the refractive index of the medium is x:1. The value of x is _______.
(Given speed of light in free space =3×108m s−1 and for the given medium µr=1 )