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Sample Space, Basics of Probability

Any activity or event that can have observable results called an experiment. More often, we are not certain about the results of the experiments. Examples below are experiments that we are not certain about their outcomes:

  1. Rolling a die and determining which of the numbers 1, 2, 3, 4, 5, and 6 lands
  2. Tossing a coin and determining heads or tails when it lands.

Each possible result of an experiment is called an outcome or a sample point. The set of all possible outcomes of an experiment is called a sample space. Any subset of a sample space is called an event.

For example, rolling a six-sided die is an experiment, since we are not sure about the result. The outcomes could be 1, 2, 3, 4, 5, or 6. The set of all these numbers establishes the sample space for this experiment. Sets {1, 2, 3} or {3, 4} is called an event for this experiment.