The speed of sound in air is roughly 1,484 m/s.

How far, in meters, would a sound wave travel in 3

seconds?

As you can see, the speed of sound changes depending on the temperature and the humidity; but if you want a round number, then something like 350 meters per secondand 1,200 feet per second are reasonable numbers to use. So sound travels 1 kilometer in roughly 3 seconds and 1 mile in roughly 5seconds.