Answer:
f_2 Â = 436 Hz
Explanation:
Given:
- Frequency of the note played f_1 = 440 Hz
- Number of beats heard per second b = 4 Hz
Find:
What was the frequency of the mis-tuned A string?
Solution:
- The beat is the difference in frequency of the notes played and is given by the expression:
                  | f_1 - f_2 | = beats
- we heard 4 beats, so
                  | f_1 - f_2 | = 4
- Plug in the value: Â Â | 440 - f_2 | = 4
Hence, Â Â Â Â Â Â Â Â Â Â Â Â f_2 Â = 436 Hz