\(P, S\), will be \(1^{\text {st }}\) and \(2^{\text {nd }}\) harmonics of closed tube.
\(P=\frac{v}{4 l}, S=\frac{v}{4 l}\)
\(Q, R\) are the \(1^{\text {st }}\) and \(2^{\text {nd }}\) harmonics of open pipe.
\(Q=\frac{v}{2 l}, R=\frac{v}{l}\)
\(\therefore P: Q: R: S=1: 2: 4: 3\)