1. The problem statement, all variables and given/known data The speed of sound along the ground is about 6.75 km/s while the speed of sound in air is 342 m/s. A very powerful explosion occurs some distance away and you feel the ground vibrate 74.0 seconds before you hear the sound of the explosion. How far away is the explosion? 2. Relevant equations d = vt 3. The attempt at a solution Not really sure how to approach this properly. There is a hint that says: "The difference in the travel times is the time given. "