A string on a guitar is supposed to vibrate at 300 Hz, but is measured at 305 Hz. By what percent should the tension in the string be adjusted to correct the tuning?

% = (305/300 - 1)*100% = 1.67%

The tension is 1.67% too high and must be decreased by 1.67%.
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To calculate the percentage change in tension required to adjust the tuning of the guitar string, we can use the formula for percentage change:

Percentage Change = (New Value - Old Value) / Old Value * 100

In this case, the old value is 300 Hz (the desired frequency) and the new value is 305 Hz (the measured frequency). Plugging these values into the formula:

Percentage Change = (305 Hz - 300 Hz) / 300 Hz * 100

Simplifying the equation:

Percentage Change = (5 Hz / 300 Hz) * 100

Percentage Change ≈ 1.67%

Therefore, the tension in the string needs to be adjusted by approximately 1.67% to correct the tuning.