What is used to express the likelihood of an event occurring?

The concept of probability is used to quantify the likelihood of an event occurring. It provides a numerical value that represents how likely an event is to happen, typically expressed as a value between 0 and 1, where 0 indicates impossibility and 1 indicates certainty. For example, if you were to roll a fair six-sided die, the probability of rolling a 4 would be 1/6, reflecting that there is one favorable outcome among six possible outcomes.

In contrast, standard deviation measures the amount of variation or dispersion of a set of values and is not used to express likelihood of occurrence. The range simply indicates the difference between the highest and lowest values in a dataset, providing no indication of probability. A Venn diagram is a visual representation used to show relationships between different sets, which can illustrate concepts related to probability but does not quantify likelihood itself. Probability is the well-defined mathematical framework for calculating and understanding the chances of different outcomes in uncertain events.