HELP! ED interview in acouple of days

Help! I have an interview in the ED in a couple of days and need some advice as to how to answer "scenario" questions. I guess since the job market is so competitive, a lot of departments are choosing to use "scenario" based questions to help filter out the weaker candidates. I am a new grad with very limited ED knowledge. If hired I would have a six month residency program for new grads. Please, any help would be greatly appreciated. Also, I need help answering this question: Tell me about a time you persisted when the odds were against you. Why did you keep trying? Right now the only thing I can come up with is successfully completing nursing school but should I gear it towards a job related task? Thanks again.