The diagram below shows two tubes partially filled with water. A student holds a $1024\ Hz$ tuning fork above the tube in two different cases. In one case, the air tube is measured by the student to be $7.0\ cm$, as pictured.
By pouring out some water, the air column is longer and is measured by the student to be $23.0\ cm$, as pictured. At both of these lengths and at no lengths between these two, the air tube resonates with the tuning fork, in effect amplifying the tuning fork's sound.
What is the calculated speed of sound that causes this to happen?