Answer:
12 m/s
Step-by-step explanation:
Standing waves are waves that are formed between two fixed points in space, so they cannot propagate, but they are just oscillations about a fixed points. Examples of standing waves are the waves in a string.
The relationship between wavelength, frequency and speed of a wave is given by the wave equation:
![v=f \lambda](https://img.qammunity.org/2021/formulas/physics/middle-school/dc8mz2det6zlp9ilwn4dj4ms3pjzgp4v1m.png)
where
v is the speed of the wave
f is its frequency
is its wavelength
For the standing wave in this problem we have:
f = 3 Hz is the frequency of the wave
is the wavelength
Solving for v, we find the velocity of the wave:
![v=(3)(4)=12 m/s](https://img.qammunity.org/2021/formulas/physics/middle-school/y5ovohl1oclbuxqtkd4uw9e50sc37kevy0.png)