$A$ closed organ pipe and an open organ pipe are tuned to the same fundamental frequency. What is the ratio of their lengths?

The fundamental frequency of a closed pipe is $400 \text{ Hz}$. If $\left(\frac{1}{3}\right)^{rd}$ length of the pipe is filled with water, the frequency of the $2^{\text{nd}}$ harmonic of the pipe will be (Neglect end correction). (in $\text{ Hz}$)

The fundamental frequency of a closed pipe of length $L$ is equal to the second overtone of a pipe open at both the ends of length $(XL)$. The value of $X$ is (Neglect end correction).

The fundamental frequency of an air column in a pipe closed at one end is $150 \ Hz$. If the same pipe is open at both ends,the frequencies produced in $Hz$ are:

In the fundamental mode,the time required for a sound wave to travel from the open end to the closed end of an air-filled pipe is $t$ seconds. What is the frequency of vibration of the air column? (Neglect end correction)

If in an experiment for determination of velocity of sound by resonance tube method using a tuning fork of $512 \ Hz$,the first resonance was observed at $30.7 \ cm$ and the second was obtained at $63.2 \ cm$,then the maximum possible error in the velocity of sound is ..... $cm/s$ (consider the actual speed of sound in air is $332 \ m/s$).