Earth’s science unit 2 lesson 15 laboratory: earthquakes epicenter

Distance between the Tulsa, OK observatory and the center of this fictional earthquake: 20 kilometers.

An earthquake generates two major seismic waves that travel through the crest at different speeds:

Let and denote the speed of the two waves, respectively. Let , resembles the time required for each waves to reach the observatory.

Both and would represent the separation between the source and the observatory. Thus

Given the difference between   and :

( given that and  )

Note that wave speed data involved in calculations above came from an external source. You shall repeat those steps with speeds indicated on the worksheet if possible.

the answer is c

tell me if wrong