Solving the A-String Puzzle: Calculating Mass from Length and Tension

[cumminatyou93]

Homework Statement

The A-string (440Hz ) on a piano is 38.9cm long and is clamped tightly at both ends. If the string is under 667-N tension, what is its mass?

I can't figure out which equations to use. Anybody know?

 

[voko]

The fundamental frequency of a vibrating string.