The problem of measuring intelligence is that most of these techniques reveal more about what we think intelligence is in a specific cultural context. Which means that individuals who rank higher in these tests are those who conform the most to a society expectancies. High level of literacy, proper nutrition during their childhood, proper education, help foster better IQ. Which of course leads to a better understanding of how your own society works, hence to a better evaluation of probabilities. If you have grown up in a family with money, you have a much better understanding of how to benefit from your investments.