To find the velocity of sound, we need to use the formula:
Velocity = Distance / Time
In this case, the distance is the depth of the well and the time is the time taken for the sound to travel up to the top of the well.
Given that the depth of the well is 67.7 meters and the time taken for the sound to reach the top is 3.91 seconds, we can substitute these values into the formula:
Velocity = 67.7 meters / 3.91 seconds
Now, we can calculate the velocity:
Velocity ≈ 17.32 meters per second
Therefore, the velocity of sound is approximately 17.32 meters per second.