Two friends prepare to play their identical guitars. During the warmup/tuning to the fundamental frequencies of the guitar, one of them hears the beats decreasing from 5 beats per second to 3 beats per second. If the fundamental note was 83 Hz on a 62.865 long string. What were the possible frequencies of the "off tuned" guitar using the best beat frequency?

What is the speed of sound of the third harmonic frequency in the string. (Please show work for both).