My chances are 20%.
Coursework: 4.00 (unweighted GPA) | 20/1086 class rank.
Test scores: 1600 (SAT) | 36 (ACT) | (AP exams) AP Human Geography - 1, AP World History: Modern - 4, AP Environmental Science - 5, AP Physics 1: Algebra-Based - 4, AP Calculus AB - 4, AP Physics 2: Algebra-Based - 5, AP French Language and Culture - 5, AP English Language and Composition - 4, AP English Literature and Composition - 5.
Extracurricular: Governor's Honors Program (Tier 3c: Strong), Key Club (Tier 2b: Very strong), Math National Honor Society (Tier 3a: Strong), Math Club (Tier 2c: Very strong), Beta Club (Tier 3c: Strong), Science Olympiad (Tier 2c: Very strong), French National Honor Society (Tier 2c: Very strong).
20% chancing is good since the real admit rate has been closer to 3% in the last 2 cycles.
No one on the CV has a 50% of getting into Caltech or MIT. It doesn't matter what you do for ECs or course rigor. I think it caps out at about 30%
Don't report any AP scores less than a 4 for Ivvy league, I can't really see anything you can improve academically I would recommend volunteering outside of school, starting a non-profit, or doing a mission project. Seeing that you're not just involved in the community but you're impacting others in a bigger spectrum. Maybe joining a club or intermural sport could help too.
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Thank you! Honestly I stressed out a bit figuring this out, this really helps.