Here is some food for thought:
1. Admission depends upon a black box calculation involving your SSAT scores (not IQ tests), grades, extracurricular activities, recommendations, essays, and whether or not you are a hooked candidate.
2. Being a hooked candidate hinges on whether you are a legacy at the prep school in question, a recruited athlete, a development admit (i.e., the child of parents who make a large donation), or an under represented minority (aka "URM"), e.g., an African American, a Native American, or a Hispanic.
3. Each school will review and compute these factors based upon what it needs to sculpt a well rounded class. In many instances, a well rounded class is comprised of individuals who stand out in one particular area, e.g.,musicians, actors, artists, athletes, etc.
4. Top non-hooked applicants to elite prep schools such as Andover and Exeter typically will be the best, or one of the very best, students in their local school; they will have SSAT scores equal to or greater than 94% ( Sort Boarding Schools by Key Criteria - Boarding School Review
; they will have outstanding extra curricular activities that reveal passion and commitment; and they will have exemplary essays and recommendations.
5. Having straight As and a 99% on the SSAT is not a guarantee of admission.
6. No one can anyone predict your chances of admissions with categorical correctness.
7. Do your own research and apply to a broad range of schools if you are unhappy with your local school.
8. Narrow your list and visit as many schools as you can preferably while they are in session.