Answer:
f = 0.65 hz
Step-by-step explanation:
Given that,
The distance between adjacent crests, wavelength = 2.4 m
6 crests are observed to move past a given point along the medium in 9.1 seconds.
We need to find the frequency of these waves.
We know that,
Frequency = no. of waves per second.

So, the frequency of these waves is equal to 0.65 Hz.