If you signed up the competition, you should go and do your best. It will be part of your EC and be part of the consideration for your BS/MD application. Whether it will have more weight or not, it is hard to say. If all your other apps are good, plus you have the medical EC is desirable to the school, you will be selected for interview. About 75% of the selected interviewee by NW will not be successful, so the chances are slim for anyone. A win in an important math competition at national level may become a part of discussion in an interview and maybe of help. But anything less than that won’t be of much consequences, as Math is not an important factor in Medical field.