Given that the frequency is f = 10 Hz
The distance between the third and sixth nodes is 54 cm.
(A) The points are the nodes, The difference between the third and sixth nodes is one and a half wavelength, so
[tex]\begin{gathered} \lambda+\frac{\lambda}{2}=54 \\ \frac{3\lambda}{2}=54\text{ cm} \\ \lambda=36\text{ cm} \\ =0.36\text{ m} \end{gathered}[/tex](B) Speed of the wave is
[tex]\begin{gathered} v=\lambda\times f \\ =3.6\text{ m/s} \end{gathered}[/tex]