Step-by-step explanation:
The frequency of a radio wave that has a wavelength of 3000m is 100 kHz
(a) Wavelength = 500 m
We know that,
[tex]f=\dfrac{c}{\lambda}\\\\f=\dfrac{3\times 10^8}{500}\\\\f=600\ kHz[/tex]
(b) Frequency, f = 800 kHz
[tex]\lambda=\dfrac{c}{f}\\\\\lambda=\dfrac{3\times 10^8}{800\times 10^3}\\\\\lambda=375\ m[/tex]
Hence, this is the required solution.