Answer:
The frequency of wave is 160Hz.
Step-by-step explanation:
Given that the formula of speed is V = f×λ where V represents speed, f is frequency and λ is wavelength.
So first thing, you have to make frequency the subject by dividing wavelength on both sides :
![v = f * λ \:](https://img.qammunity.org/2021/formulas/physics/middle-school/1ch4ma99axi896ot2vz9mikn314lozttrw.png)
![v / λ = f * λ / λ](https://img.qammunity.org/2021/formulas/physics/middle-school/bk9om6xfz76w1dung0kj465tsy9muw2389.png)
![f = (v)/(λ)](https://img.qammunity.org/2021/formulas/physics/middle-school/x5edhyq7t6v7ans6yhy1fd5kxbvohz0qbf.png)
Next you have to substitute the value of v and f into the formula :
Let λ = 2.5m,
Let v = 400m/s,
![f = (400)/(2.5)](https://img.qammunity.org/2021/formulas/physics/middle-school/t2w6sdniemjkvyt3z89mjt7b07aej79nug.png)
![f = 160Hz](https://img.qammunity.org/2021/formulas/physics/middle-school/6xlxobtpbpeac0mwrrz49mkz4m13raw7b4.png)