Answer:
Wavelength of the incident wave in air = 1 m
Wavelength of the incident wave in medium 2 = 0.33 m
Intrinsic impedance of media 1 = 377 ohms
Intrinsic impedance of media 2 = 125.68 ohms
Check the explanation section for a better understanding
Explanation:
a) Wavelength of the incident wave in air
The frequency of the electromagnetic wave in air, f = 300 MHz = 3 * 10⁸ Hz
Speed of light in air, c = 3 * 10⁸ Hz
Wavelength of the incident wave in air:

Wavelength of the incident wave in medium 2
The refractive index of air in the lossless dielectric medium:


b) Intrinsic impedances of media 1 and media 2
The intrinsic impedance of media 1 is given as:

Permeability of free space, 
Permittivity for air, 


The intrinsic impedance of media 2 is given as:

Permeability of free space, 
Permittivity for air, 
ϵr = 9


c) The reflection coefficient,r and the transmission coefficient,t at the boundary.
Reflection coefficient, 
You didn't put the refractive index at the boundary in the question, you can substitute it into the formula above to find it.

Transmission coefficient at the boundary, t = r -1
d) The amplitude of the incident electric field is 
Maximum amplitudes in the total field is given by:
and 
E = 10r, E = 10t