What should be the frequency of beats so that they can be heard clearly in the case of sound?

The wavelengths of two sound notes in air are $\frac{40}{195} \,m$ and $\frac{40}{193} \,m$. Each note produces $9$ beats per second separately with a third note of fixed frequency. The velocity of sound in air in $m/s$ is

In case of beats,produced by the superposition of two waves of equal amplitudes,if maximum intensity is $x$ times the intensity of a superposing wave,then $x =$ ......

$A$ set of $20$ tuning forks is arranged in a series of increasing frequencies. If each fork gives $4 \; Hz$ beats with respect to the preceding fork and the frequency of the last fork is twice the frequency of the first,then the frequency of the last fork is $\dots \; Hz$.

$A$ source of sound gives five beats per second when sounded with another source of frequency $100 \, s^{-1}$. The second harmonic of the source together with a source of frequency $205 \, s^{-1}$ gives five beats per second. What is the frequency of the source in $s^{-1}$?

When a guitar string is sounded with a $440\, Hz$ tuning fork,a beat frequency of $5\, Hz$ is heard. If the experiment is repeated with a tuning fork of $437\, Hz$,the beat frequency is $8\, Hz$. The string frequency $(Hz)$ is