compound event An event with more than one outcome. equally likely Having the same likelihood of occurring, such that in a large number of trials, two equally likely outcomes would happen roughly the same number of times. event A collection of possible outcomes, often describable using a common characteristic, such as rolling an even number with a die or picking a card from a specific suit. event space The set of possible outcomes in an event: for example, the event “rolling an even number” on a die has the event space of 2, 4, and 6. Fundamental Counting Principle If one event has p possible outcomes, and another event has m possible outcomes, then there are a total of p • m possible outcomes for the two events. outcome A result of a trial. probability A measure of how likely it is that something will occur. sample space The set of all possible outcomes. simple event An event with only one outcome. tree diagram A diagram that shows the choices or random outcomes from multiple trials, using branches for each new outcomes. trial A random action or series of actions.