Probability is the chance of something occuring. 120% is not realistic in real world examples, because the probability standard ranges from "definitely will not happen" to "definitely will happen", meaning a 0% chance of it occurring to 100% chance of it occurring. The only time 100.0%+ will be applicable are typically in simulations, which allows for such to counterbalance any negatives percentages that is allocated to the target. However, in the real world, it will never go over 100%.