Apiano tuner is tuning a string which should have a frequency of 440 hz. she knows the pitch is too high and she hears 4 beats per second. what is the frequency of the piano string?

444 Hz

Explanation:

When two notes of slightly different frequency interfere with each other, they form a resultant wave whose frequency is called beat frequency, which is given by the difference between the frequencies of the two notes:

In this case, we have

is the frequency of the tuner

is the frequency of the string

is the beat frequency (4 beats per second)

We also know that the frequency of the string is too high compared to the tuner, so

so we can find the frequency of the string: