The velocity of the wave is 12 m/s.
Explanation:
We know the formula for the velocity of wave as:
v = f [tex]\lambda[/tex]
where,
v= velocity of wave
f = frequency of wave
[tex]\lambda[/tex] = wavelength of wave
Substituting the values we get;
v = 3 × 4 m/s
∴ v = 12 m/s
In this way we calculated the velocity of wave as 12 m/s.