Answer:
437Hz
Explanation:
if two sound waves have a little difference in frequencies [tex]f_{a}[/tex]
and [tex]f_{a}<f_{b}[/tex]
interfere, the resulting sound wave produces a beat.
Given:
[tex]f_{a}=440Hz[/tex]
[tex]f_{b}=frequency\ of\ the\ sound\ emitted by\ the\ piano\ key[/tex]
[tex]f_{beat}=frequency\ of\ beat[/tex]
where
[tex]f_{beat}=\frac{number\ of\ beat}{time} [/tex]
[tex]f_{beat}=\frac{15beats}{5}=3Hz[/tex]
[tex]f_{beat}=f_{a}-f_{b}[/tex]
[tex]f_{b}=f_{a}-f_{beat}[/tex] = 440Hz - 3Hz = 437Hz
