Simplify the following text for a Grade 3 native English-speaking person.
Original: The middle 50 percent of the incoming class earned a high school GPA of 3.60 to 3.90 .
Simplified: 98 % of the university 's class of 2006 had a high school GPA of 3.0 and higher , while the middle 50 % of the class had a high school GPA of 3.60 to 3.90 .