Earthquakes generate sound waves inside Earth. Unlike a gas, Earth can experience both transverse (S) and longitudinal (P) sound waves. Typically, the speed of S waves is about 4.5 km/s and that of P waves 8 km/s. A seismograph records P and S waves from an earthquake. The first P waves arrive 3.9 min before the first S waves. Assuming the waves traveled in a straight line, how far away did the earthquake occur?

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