Wanted: a sound, fair and practical means of ending the charade that has semi-pro athletes masquerading as college students.

Proposition 48, the controversial proposal of the National Collegiate Athletic Association, was supposed to be the answer. The rule, which was to have gone into effect in August 1986, would require that in order to be eligible for college sports, student-athletes would have to have at least a C average in their high schools and also score at least a combined 700 on the Scholastic Aptitude Test.

It seemed sound enough. A perfect SAT score is 1,600. The median 25th percentile for freshmen nationwide is 870. You get 400 for getting your name right. Anybody who couldn't come up with another 300 points worth of correct answers has no business in college, right?

But was it fair? The NCAA recently released the results of a $200,000 study it commissioned to answer that question. The crucial finding: six out of every seven black male basketball players and three out of every four black football players in the top athletic universities wouldn't have qualified for first-year eligibility under the proposed NCAA rule. (A third of the white male basketball players and half of the white footballers wouldn't have qualified either.)

On the other hand, the rule would have done a good job of identifying high- risk students. Approximately 48 percent of the black males who met the requirements of Proposition 48 (compared with only 28 percent of those who didn't) went on to earn diplomas.

So maybe you're willing to swallow hard and accept a rule that weeds out the academic bums even though it is disproportionate in its negative impact on black athletes. But what about the test of practicality?

There are really two practical questions. First, there is the question of what do with an athlete who thinks he may be talented enough for a professional sports career but who happens to be a bit slow with the books. If his sport is baseball, no problem. He simply hooks up with a minor league team and waits for the majors to discover him. But for basketball and football, college athletics are the minor leagues. Deny the prospective professional point guard a chance at college and you have effectively denied him a chance at a million- dollar contract in the National Basketball Association, a chance to earn good money at the thing he does best.

That's a problem, all right, but why is it a problem that the colleges must solve? That's where the second practical question comes in. Big-time collegiate basketball and football are major income producers for the universities. What would be the impact on that income if six out of every seven black basketball players and three-quarters of the black footballers couldn't play? How many times are fans going to spend a Saturday afternoon watching the equivalent of Harvard-Colgate on TV?

On the other hand, nobody likes the idea of college athletes only pretending to be students. Maybe you'd settle for the other part of Proposition 48: the requirement that the prospective college player be at least an average student in high school.

Well, consider the case of Mount Vernon High School's football team, which recently forfeited four victories because one of its players was ineligible. The young man in question, a transfer from the District's Roosevelt High School, thought he had another semester's eligibilty because he had laid out a semester at Roosevelt, when he hadn't gone to school a single day after Christmas, he said.

The problem: his Roosevelt transcript showed him earning a grade of C for the semester he wasn't there.

The NCAA will meet in January to decide on yet another set of modifications to solve the problem. It's hard to be optimistic that they will come up with anything that will meet the tests of soundness, fairness and practicality.