In the resonance experiment, two air columns (closed at one end) of \(100 ~\text{cm}\) and \(120 ~\text{cm}\) long, give \(15\) beats per second when each one is sounding in the respective fundamental modes. The velocity of sound in the air column is:
1. \(335~\text{m/s} \)
2. \(340~\text{m/s} \)
3. \(360~\text{m/s} \)
4. \(370~\text{m/s} \)