If we want to know how often events occur out in the real world, why can't we just observe them lots of times and then calculate probabilities? Mark all that apply. If we want to know how often events occur out in the real world, why can't we just observe them lots of times and then calculate probabilities? Mark all that apply. The real world is too messy You would not get accurate results if you tried that Sometimes that approach is too expensive Some things do not happen very often