What would be an example of a one point conceptual error in this problem? The only conceptual error that I can imagine is the perimeter - isn't the one point deduction specific to this case. I understand that it trivializes the problem but what else could they do... did anyone give 2 points for using the perimeter? This was not my question for grading but I just thinking about it for future reference.
This was a tough exam to grade and the time pressure was ridiculous!!!