Complex sentence: Harvard School of Public Health is one of the most selective and prestigious public health schools in the world, whose middle 50 percent of the class in 2006 had an incoming GPA between 3.50 and 3.75 (out of 4.0).
Split into simpler sentences: Harvard School of Public Health is one of the most selective and prestigious public health schools in the world. In 2006, the middle 50 percent of the incoming class had an incoming GPA between 3.50 and 3.75 (out of 4.0).