We're not going to do your homework for you, but we will say that the
oscillation frequency, the wave speed, and the wavelength are related.
The oscillation frequency is the reciprocal of the amount of time
it takes between one crest of the wave to go past and the next crest to
go past. The wavelength is the distance between these crests. Distance
divided by time is speed.
So speed = Frequency*Wavelength. You need to know what the speed
of a FM radio wave is, and the speed of a radar signal. You can usually
approximate that with the speed of light, but the speed of light in
materials (air, for example) will be just a smidge less than the speed
of light in vacuum.
MHz means millions of cycles per second.
GHz means thousands of millions of cycles per second ("billions" to Americans -- the Brits may use different words).
(republished on 07/28/06)