It is hard to say. I finished MBA at 36, but I was not the oldest by far. FT MBA are usually younger, PT MBA are older. Also, some schools, Cranfield for example, recruit older students. However, once you got your MBA, you need to play your cards well to land on the job you want. Some career services will help you with this, some won't, it depends on school. Also, if you end up in a top 10 MBA in the world, then it is way higher chance to change your life. I am not saying for better - some jobs will demand even more time to spend at work