The answer depends on how you look at it. Your teacher simplifies the question by assuming the company manufactures infinitely many M&M's, while you assume they make a countable number. If they make infinite M&M's then you're chance does not increase, but if they make a non-infinite (but high) number then your chances do increase (if ever so slightly). Seeing how they, probably, make countless M&M's your odds increase so very slightly that you might call it none. It all depends on whether you abstract that part of the question or not. But for all intends and purposes the answer is that there is no increase, while being mathematically precise you can only state the number approaches zero but will never reach it.