A violin string has a length of 0.350 m and is tuned to concert G, with f = 392 Hz.

Where must the violinist place her finger to play concert A, with f = 430 Hz?

If this position is to remain correct to half the width of a finger (that is, to within 0.600 cm), what is the maximum allowable percentage change in the string tension?

I have no idea how to solve this problem or even the equations involved with it. It is due in a few hours. Any help would be much appreciated! Thank you!