Good man, Shortie. Correct!! For others, its actually a smart question, no silly trick involved and rarely does any member of the public get it right. If you'd like, and don't be ashamed, I can explain how and why "8" is the correct answer.
Don't mean to argue, but ... it appears you're making an assumption, not stated in the initial question, that somehow Dow Jones is aware that 7 cigarette butts would magically turn into a full cigarette. Further, you are assuming that Dow Jones can in fact collect up to 7 butts, in addition to keeping the butts from the magic cigarettes as he goes. In the scenario laid out, Mr Jones would probably smoke the butts as he found them to avoid the risk that someone would steal his collection or injure him in the process of stealing his collection. I can understand "8" as the target answer, but I think the real-world answer would be around 39 butts (assuming he tosses the butts where the tobacco is completely gone, and these are around 15% of total butts).
Arguing is just fine, but allow me to invoke a fundamental HERD principle that works ALL the time ..... hidden and deeply embedded under a misunderstanding or misduplication is a misunderstood word, symbol or concept. In other words, a misunderstood word, symbol or concept is the underlying cause of failure to grasp ....
For everyone ... he finds the first 7 butts, boom, magic, he has a full cigarette, he smokes this, but even the mighty Dow gotta leave a butt behind. Therefore for every 7 butts he finds he leaves a butt behind. Therefore when he finishes smoking the obvious 7 cigs he still has 7 butts left, which become another full cig. So "8" is the answer.
For the forest, I'd guess it's something like distance from the edge to the center; once he passes the center, he's then running out of the forest. This answers "how far can he run", as in what is the maximum possible -- not "what is the probability he would actually pass through the center (or any other specified spot)".
What I want to know is, if you have been here 5 years and you can still talk about your teacher having conversations with your parents, just how young are you?