2nd overtone of an open organ pipe = \(\frac{3v}{2L_0}\)
1st overtone of an closed organ pipe = \(\frac{3v}{4L_C}\)
\(\frac{3v}{3L_0} = \frac{3v}{4L_C}\)
\(\frac{1}{L_0}\) = \(\frac{1}{2L_C}\)
L0 = 2LC
The length of the open pipe is two times of the length of the closed pipe