Sorry that I had to use an image file, I was having a lot of trouble using the Latex system. Ok... We know the amplitude of the oscillations, and the force per person, so all we need to do is find Fmax, by finding other values and substituting into the equation for amplitude. By using the equation for oscillation of an underdamped system I have found that b=m/3T, where T is the period of the undriven, undamped system, but I'm not sure how to find T in order to get a numerical value for b. I could find it if I knew k, the force constant of the system, but I have no idea how to find that. So, I guess that my question is, how do I find the k of the system? If I know that, I think I'll be able to solve the rest of the problem. Thanks!