172726 Two vibrating strings ' $A$ ' and ' $B$ ' produce beats of frequency $8 \mathrm{~Hz}$. The beat frequency is found to reduce to $4 \mathrm{~Hz}$ if the tension in the string ' $\mathrm{A}$ ' is slightly reduced. If the original frequency of $A$ is $320 \mathrm{~Hz}$ then the frequency of ' $B$ ' is
172726 Two vibrating strings ' $A$ ' and ' $B$ ' produce beats of frequency $8 \mathrm{~Hz}$. The beat frequency is found to reduce to $4 \mathrm{~Hz}$ if the tension in the string ' $\mathrm{A}$ ' is slightly reduced. If the original frequency of $A$ is $320 \mathrm{~Hz}$ then the frequency of ' $B$ ' is
172726 Two vibrating strings ' $A$ ' and ' $B$ ' produce beats of frequency $8 \mathrm{~Hz}$. The beat frequency is found to reduce to $4 \mathrm{~Hz}$ if the tension in the string ' $\mathrm{A}$ ' is slightly reduced. If the original frequency of $A$ is $320 \mathrm{~Hz}$ then the frequency of ' $B$ ' is
172726 Two vibrating strings ' $A$ ' and ' $B$ ' produce beats of frequency $8 \mathrm{~Hz}$. The beat frequency is found to reduce to $4 \mathrm{~Hz}$ if the tension in the string ' $\mathrm{A}$ ' is slightly reduced. If the original frequency of $A$ is $320 \mathrm{~Hz}$ then the frequency of ' $B$ ' is