What does the term "event" refer to in probability?

The term "event" in probability refers to a collection of outcomes from a particular experiment or random process. It encompasses all the possible results that can occur from performing an experiment, which is key to understanding how probability works. For example, when rolling a six-sided die, the event of rolling an even number includes the outcomes {2, 4, 6}.

By defining events this way, you can analyze and calculate probabilities for various scenarios, as events can be simple (just one outcome) or compound (a combination of multiple outcomes). This understanding of events is fundamental in probability theory, as it allows you to assess the likelihood of different outcomes occurring together.

The other options focus on narrower or unrelated concepts. A single outcome only describes a specific result, which does not fully capture the broader idea of an event. The sum of random variables represents a calculation rather than a collection of outcomes. The term theoretical probability refers to the calculation derived from a model based on ideal conditions rather than the concept of an event itself.