Probability is the reverse of statistics; in probability, we use info about the pop to infer the probable nature of the sample. Experiment- an act or process of observation that leads to a single outcome that cannot be predicted with certainty. Sample points- the most basic and observable result obtained from an experiment. Sample space- the collection of all the possible sample points of an experiment. The probability of a sample point is a number between 0 and 1 that measures the likelihood that the outcome will occur when the experiment is performed. Probability rules for sample points: all sample point probabilities must lie between 0 and 1, the probabilities of all the sample points within a sample space must sum to 1. Event- a speci c collection of sample points. The probability of event a is calculated by summing the probabilities of the sample points in the sample space for a.