1. The problem statement, all variables and given/known data A pipe resonates at successive frequencies of 540 Hz, 450 Hz, and 350Hz. Is this an open or a closed pipe? 2. Relevant equations -- 3. The attempt at a solution My assumption is that because the harmonics of an open pipe are odd number multiples of the fundamental frequency (1f, 3f, 5f), and ∵ the difference between the frequencies is the fundamental frequency (I think?). The fundamental frequency is ∴ around 100 (?). And ∵ the frequencies go up by ~100 each time, it's an open pipe, as it's harmonics are even number multiples (1f, 2f, 4f, 6f). I don't think my assumptions are correct. Any help is appreciated, thanks. EDIT: Is it possible to determine the fundamental frequency from the given frequencies? I'm beginning to think that the fundamental frequency is the difference between those frequencies, divided by two. Because to get from on harmonic to the next, we multiply by two to get from one freq to the next, with the exception of the even number multiples(1f→2f).