Question:
A 
string is stretched between fixed supports. It is observed
to have resonant frequencies of 
and 
, and no
other resonant frequencies between these two.
for this string.
Solution:
For this fixed end string we have that the resonant frequencies are
.
We are given that
, and therefore
n=3 has a frequency of .
Hence the lowest frequency, for n=1 is 
.
The wave speed is 
.