The distance between two crests is 9.5 m, this means the wavelength of the waves is
[tex]\lambda=9.5 m[/tex]
The fisherman also notices that crests pass every 4.4 s, so the frequency of the wave
[tex]f=4.4 s^{-1} = 4.4 Hz[/tex]
Therefore, we can use the basic relationship between frequency and wavelength of a wave to find the speed of the waves:
[tex]v=f \lambda=(4.4 Hz)(9.5 m)=41.8 m/s[/tex]
