To compute for the frequency of the wave, we must have its speed and wavelength. Wavelength is can be measured through the distance between two crests. Thus, the wave's wavelength is 6 m. And given that it travels at a speed of 13 m/s, we have
[tex] f = \frac{v}{\lambda} \\ f = \frac{13 m/s}{6 m}[/tex]
Thus, we have [tex] f = 2.17 Hz [/tex].
Answer: 2.17 Hz