Using Time Travel Curves to Find Information About S Waves

[rh10031994]

Hi, I am currently working on this project: http://www.sciencebuddies.org/science-fair-projects/project_ideas/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. I don't get how to this, but if someone would provide an example or an explanation as to how this works, that would be great!