Answer :
Given that,
The speed of a wave, v = 200 m/s
Wavelength, [tex]\lambda=2\ m[/tex]
We need to find the frequency of this wave. The relation between wavelength, frequency and the speed is given by :
[tex]v=f\lambda\\\\f=\dfrac{v}{\lambda}\\\\f=\dfrac{200\ m/s}{2\ m}\\\\f=100\ Hz[/tex]
So, the frequency of this wave is 100 Hz.