Physics: What harmonic number are these two frequencies listed.

Question

A pop bottle style instrument is played being open at one end closed at the other, if two successive frequencies, 350 Hz and 490 Hz, are produced, what is the fundamental frequency, and what harmonic number are these two frequencies listed.

Answer 1

The ratio of 490 to 350 is   7 to 5.   Since resonators closed at one end and open at the other have only odd harmonics, the 7th harmonic  (490 Hz) is the one that is next in sequence after the 5th (350 Hz).   Thus the fundamental is 350/5 = 70 Hz.