Thread: Use Time Travel Curve to Get Information Abo S Wave

Hi, I am currently working on this project: http://www.sciencebuddies.org/scienc...Geo_p022.shtml
I have plotted the seismic waves of an earthquake and drawn the time travel curves, but I cannot figure out the last two steps:
- At what distance from the quake in degrees does the primary S-wave no longer appear?
- What is the maximum distance at which the primary S-wave appears?
I am doing this for only one earthquake, and I am running out of time. Please help and explain how to do this!