The diagram illustrates three complete cycles over a distance of 9 m. Therefore, the wavelength \lambda is 9 m / 3 = 3 m. The time t = 0.6 s corresponds to two periods (based on the labeling in the diagram spanning two cycles). Therefore, the period T is \(\frac{0.6 s }{2}\) = 0.3 s. The speed of the wave v is given by v = \(\frac{\lambda }{\text{T}}\) = \(\frac{3 m }{0.3 s}\) = 10 m/s.