Earthquakes produce several types of shock waves. The most well known are the P-waves (P for $primary$ or $pressure$) and the S-waves (S for $secondary$ or $shear$). In the earth's crust, P-waves travel at about 6.5 km/s and S-waves move at about 3.5 km/s. The time delay between the arrival of these two waves at a seismic recording station tells geologists how far away an earthquake occurred. If the time delay is 33 s, how far from the seismic station did the earthquake occur?