The G string on a guitar, when properly tuned, should vibrate at in its first harmonic $($which is the dominant harmonic you hear when you pluck the string$).$ Suppose two identical guitars with identical strings are tuned properly at first. Later, the tension in the G string of one of the guitars is decreased slightly so that when the two G strings are now played simultaneously, a beat can be heard. By what percent did the tension change? $($the percent change will be positive for an increase and negative for a decrease$)$