I have a problem on my sheet that is confusing me. The problem states The world's largest guitar, which was built by high school students in Indiana, has strings that are 9.0 long. The fundamental vibration that can be induced on each string has a wavelength equal to twice the string's length. If the wave speed in a string is 9.0 x 10 squared m/s what is the frequency of vibration? The given is f=50.0 Hz L= 9.0 m My question is where did they get 50.0 Hz when it's not stated in the problem. Or am I reading the problem wrong.