Two sound waves of slightly different frequencies propagating in the same direction produce beats due to

$56$ tuning forks are arranged in increasing order of frequencies in a series such that each fork gives $4 \text{ beats per second}$ with the previous one. The frequency of the last fork is the octave of the first. The frequency of the first fork is ..... $Hz$.

There are three sources of sound of equal intensity with frequencies $400, 401$ and $402\, vib/sec.$ The number of beats heard per second is

$25$ tuning forks are arranged in series in the order of decreasing frequency. Any two successive forks produce $3 \, Hz$ beats. If the frequency of the first tuning fork is the octave of the last fork,then the frequency of the $21^{st}$ fork is .... $Hz$

Two sound waves of wavelengths $\lambda_1$ and $\lambda_2$ $(\lambda_2 > \lambda_1)$ produce $n$ beats per second. The speed of sound is:

The sound waves of wavelengths $5 \,m$ and $6 \,m$ produce $30$ beats in $3 \,s$. The velocity of sound is (in $\,m/s$)