If this is your first EMT job and have no previous experience I don't think they'll ask you anything too complicated if they do give you a scenario question, in fact the 2 companies I worked for, neither gave me a scenario question nor did they have a skills test. I would say prepare for it like its a regular job interview, a big part of this job is customer service, sell yourself with that. Also they'll probably ask you the basic stuff, "why do you want to be an EMT?" and "Why do you want to work for us?".