If the frequencies of two component waves are 24hz and 20hz, they should produce beats per second

4 beats per second

Explanation:

When two waves of slightly different frequencies overlap, they produce an interference pattern called beat, which consists in a periodic oscillation whose frequency is called beat frequency.

The beat frequency is equal to the absolute value of the difference between the frequencies of the two original waves:

In this problem, the frequencies of the two waves are:

So, the beat frequency is

which corresponds to 4 beats per second.