"The review looked at 1,212 student records randomly selected from the 5,496 graduated seniors who had grades changed after a year-end deadline in 2016 or 2017. If the 24.5 percent rate held over the entire group of seniors with grade changes, it would translate to about 1,600 students."
https://wtop.com/prince-georges-county/2017/11/audit-25-percent-prince-georges-high-school-graduates-may-not-met-requirements/
Link to the full audit report:
http://www.pgcps.org/graduation-audit/