When a tuning fork is vibrating,the vibrations of the two prongs

When two waves of almost equal frequencies $v_1$ and $v_2$ reach a point simultaneously,the time interval between successive maxima is

The frequencies of three tuning forks $A$,$B$,and $C$ are related as $n_{A} > n_{B} > n_{C}$. When the forks $A$ and $B$ are sounded together,the number of beats produced per second is $n_1$. When forks $A$ and $C$ are sounded together,the number of beats produced per second is $n_2$. How many beats are produced per second when forks $B$ and $C$ are sounded together?

Two sound sources,when sounded simultaneously,produce four beats in $0.25 \ s$. The difference in their frequencies must be: (in $Hz$)

Two sources of sound placed close to each other are emitting progressive waves given by $y_1 = 4 \sin(600\pi t)$ and $y_2 = 5 \sin(608\pi t)$. An observer located near these two sources of sound will hear:

$A$ source of frequency $\nu$ gives $5$ beats/second when sounded with a source of frequency $200 \;Hz$. The second harmonic of frequency $2\nu$ of the source gives $10$ beats/second when sounded with a source of frequency $420 \;Hz$. The value of $\nu$ is .... $Hz$.