means very little ...just a negligible pointer to ongoing systemic failure....
anybody with money knows whether a kid has 100 marks he/she can easily end up in a 'good' school; get a D+ go for a bridging course or get a job then go to university and be whatever money can buy... the kid if poor will start selling mandazi or slogging off in dirty jobs
on the other hand a poor kid who gets 400 and misses on Mastercard/Equity scholarship, bursaries or if a big shot doesn't attend the harambee she/he is likely to end up in a local school ..... a lucky isolated few will make the cut off point, go to universities and then get out to hit the tarmac .. begging for job or sleeping place from the kids who got 100......
the normal distribution may hold true