Education database company Niche compiled the rankings by weighing a school's SAT/ACT scores, average score of colleges attended by graduates and percentage of graduates who attend four-year schools after graduation, Business Insider said.
Brunswick boasts a composite SAT score of 2040 and an average ACT score of 31. It also has a four-year college matriculation rate of 96 percent, the report said.
Three private schools in New York City were ranked in the top 10, including: the Dalton School at 10th, Trinity School at seventh and the Horace Mann School at fifth.
Two schools from Westchester County in New York also made the list: Rye Country Day School and the Hackley School in Tarrytown.
The title of smartest private school went to Castilleja School in Palo Alto, Calif.
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