The first overtone of an open organ pipe beats with the first overtone of a closed organ pipe with a beat frequency of 2.2 Hz. The fundamental frequency of the closed organ  pipe is 110 Hz. The lengths of the pipes are

For closed organ pipefc=(2n−1)v4Lc with n=1,2,…While for open organ pipe f0=nv2L∘ with n=1,2,…According to given problemfC=V4Lc=110  i.e.,  Lc=3304×110=0.75mFurthermore3v4Lc~2v2L∘=2.2  or  330L∘=330∓2.2  as 3V4Lc=3fC=330 i.e.,  L∘=330330∓2.2⇒L∘=1.0067m  or  0.9937m