Probability

Probability, branch of mathematics that deals with the likelihood that an event will occur. Most commonly, the number of possible outcomes is counted, and the probability of any particular outcome is expressed as a fraction between 0 and 1. For instance, in rolling 2 dice there are 36 possible outcomes. Only one of these is that a 12 will turn up (a 6 on each die). The chance of rolling a 12 is therefore 1/36. On the other hand, there are 6 possible ways of rolling a 7: 1–6, 6–1, 5–2, 2–5, 3–4, 4–3. The chance of rolling a 7 is therefore 1/6. As more complicated theories and problems arise, more sophisticated techniques arise, such as permutations and combinations. Probability theory has contributed vital understanding in many fields of physics, including statistical mechanics. Its importance in science has risen dramatically in recent decades. Statistics, a related field, is the application of probability theory to data collected from research samples.

See also: Mathematics.