Answer:
[tex]f' = 410 Hz[/tex]
Explanation:
Initially when fundamental frequency of the string is
f = 328 Hz
let the length of the string is Lo at this time
so we will have
[tex]f = \frac{2v}{L_o}[/tex]
now the length is shorten so that the frequency will change
final length is four fifth of the original length
so here we have
[tex]L = \frac{4L_o}{5}[/tex]
now we have
[tex]f' = \frac{2v}{4L_o/5}[/tex]
[tex]f' = \frac{5v}{2L_o}[/tex]
now we have
[tex]\frac{f'}{f} = \frac{5v/2L_o}{2v/L_o}[/tex]
so we have
[tex]\frac{f'}{f} = \frac{5}{4}[/tex]
so the new fundamental frequency will be
[tex]f' = \frac{5}{4}(328)[/tex]
[tex]f' = 410 Hz[/tex]