While attempting to tune the note C at 517 Hz, a piano tuner hears 6 beats/s between a reference oscillator and the string.
(a) What are the possible frequencies of the string?
(b) When she tightens the string slightly, she hears 7 beats/s. What is the frequency of the string now?
(c) By what percentage should the piano tuner now change the tension in the string to bring it into tune? (Give a positive answer for an increase in the tension, or a negative answer for a decrease in the tension.)