You will have a pre-interview with the office supervisor who is at this time a really nice person. If she likes you then you get a second interview which is a "pier interview" where 3 of the office workers will ask you a series or "behavior based" questions. Don't worry so much about what you're answer is. It's more about what you're answer says about the kind of person you are. They are looking for someone who will fit in well with the group.