For sound waves, if the number of nodes for the 5^ th harmonic of an open-ended pipe is n and that for the 9^ th harmonic of the same pipe with one…

For sound waves, if the number of nodes for the $\displaystyle 5^{\text {th }}$ harmonic of an open-ended pipe is $\displaystyle n$ and that for the $\displaystyle 9^{\text {th }}$ harmonic of the same pipe with one of its ends closed is $\displaystyle m$, the ratio $\displaystyle \frac{n}{m}$ is :