Are you reading Lord of the Flies?
Anyway, I usually hate these things that make me pretend I'm an age I'm not, so I'm not going to pretend that I'm not an adult when I am one. But a big reason for that is because I really don't see why it matters if I'm two years younger than I am now. There's not that much of a physical difference between 19 years old and 17 years old, and in these situations, I don't think people look to the oldest for the leadership, but rather to people who they think will be the strongest and most appropriate leader. Most of the time, it just so happens that it's an adult who fills that role, but just because someone may be older shouldn't mean anything. In my experience, while most adults tend to be stronger than most of the youth, they don't really seem as logical or forward thinking as the younger generations anymore.
I don't really know how I'll survive. I've never been in that kind of situation, and I don't watch survivor, but I would probably first focusing on establishing a leadership type of thing within our group, finding a safe place to go to live for the time there, and live day-to-day, rather than thinking and worrying about the next. But that's probably harder to be done than said. I'd probably end up having to sacrifice my vegetarianism to survive since I don't know what there will be to eat there. Um... yeah, I really don't know what else to say. There isn't really much to go on.
What's that movie where a guy is stranded on an island and paints a face on a volleyball? I imagine my experience would be that mixed with Lord of the Flies. People are going to resort to things they wouldn't normally to survive. They're going to lose common sense, they're going to make decisions on a whim. To really state how you're going to survive when you throw in the fickleness of the human race as a whole isn't very easy. I don't know what I'm going to end up doing after all the time stranded, much less the mindset of other people and how that will be affected as a result. So this question is just a really hard circumstance to give an answer to.