[JesseK]

These sound like the types of conflicts that occur between professional engineers and Program Managers. In all honesty, the mentorship may have made a decision based upon information that you didn't know, or more probably they made a decision based upon information you simply do not like. The info could have ranged from everything dealing with the lack of time management to how well she spoke under pressure. It's not really worth conjecture though.

The only thing you're 'entitled' to is an explanation, but only if you're not confronting in your approach to the mentor(s) who made the decision. Past that, it's not really worth it in your last year of high school. If you're going to Atlanta then enjoy the Championships; if not then enjoy the rest of the school year. Either way, regardless of whether it was a weighted decision, impulsive decision, success or mistake the only thing you can really do is get over it and move on.

The only reason you would want an explanation is so that you do not make the same mistake again in the future.