Answer:
The longest wavelength is 3 m when speed of wave was 300 m/s and frequency was 100 hertz.

Step-by-step explanation:
Wavelength is equal to ratio of speed of the wave to the frequency of the wave.
1) Speed = 700 m/s and frequency = 350 Hz =

Wavelength of the wave:

2) Speed = 300 m/s and frequency = 100 Hz =

Wavelength of the wave:

3) Speed = 1,000 m/s and frequency = 1,000 Hz =

Wavelength of the wave:

The longest wavelength is 3 m when speed of wave was 300 m/s and frequency was 100 hertz.