Paul Tough in the New York Times has a long article " Who Gets to Graduate " on the high college dropout rate of working class kids, focusing on some black girl from a mediocre Dallas area high school who gets into desirable U. of Texas at Austin, the state flagship school, despite being down around the 10th percentile among freshmen:

Her senior-year G.P.A. was 3.50, placing her 39th out of 559 students in her graduating class. She got a 22 on the ACT, the equivalent of about a 1,030 on the SAT — not stellar, but above average.

The 25th percentile at UT Austin on the ACT is 25 and the 75th percentile is 31. I believe 30 is at the 95th percentile among takers of the ACT, so maybe 97th among the overall population. There are a lot of smart kids at UT Austin. She got in, barely, under George W. Bush's plan to admit the top X percent of Texas high schools' graduating classes, even though 3.5 isn't very good these days.

Not surprisingly, like many freshmen, she struggled. Traditionally, state flagship universities are harder to graduate from than more prestigious private colleges because they spend less per student and don't feel a commitment to parents to deliver a degree in return for a huge amount of tuition.

After Sputnik, America focused on finding and educating the highest potential students. And 12 years later, Neil Armstrong walked on the moon. But then came other priorities like civil rights.

The solution touted in the article is for famous public universities to give low test score students much more handholding, such as improving the teacher to student ratio in a special chemistry class for low test score students by 10 to 1. But, the article makes clear, it's absolutely essential that nobody on campuses notices that there are all these special courses for the not so bright because that would ruin their self-esteem and then the magic would vanish. Or something.