$\frac{F+4}{F+1}=\sqrt{\frac{273+51}{273+16}}$
$\frac{f+4}{f+1}=\sqrt{\frac{324}{289}}$
$\frac{f+4}{f+1}=\frac{18}{17}$
$f=50 \,Hz$

where $x$ and $y$ are in $m$ and $t$ is in $s$. The length of the string is $1.5\, m$ and its mass is $3.0 \times 10^{-2} \,kg$, then tension in string is ..... $N$



