With respect to his/her academic interests, you will find a few available resources:
■ Amherst, Williams, Hamilton, Bowdoin, Haverford, Pomona, Reed and Carleton are some of the highly selective LACs that appear in a Princeton Review sampling, “Great schools for Mathematics Majors.”
■ Highly rated economics departments in this analysis are notable for their faculty scholarship: https://ideas.repec.org/top/top.uslacecon.html.
■ These schools, based on survey results, are notable for their classroom experiences: https://www.princetonreview.com/college-rankings?rankings=best-classroom-experience.
Transfer acceptance rates at the above referenced colleges vary, but are equivalent to those for first-year applicants in at least some cases.