Calculating probabilities

Apply probability rules after checking event relationships and conditions.

Meaning

For a union, subtract the overlap once. For successive events, multiply probabilities that account for the conditions. Complements can simplify complicated cases.

Example

On a fair six-sided die, the probability of an even result or a multiple of 3 is The result 6 was counted twice and subtracted once.Multiplying any two event probabilities does not always give the probability that both occur. Use conditional probability when they are not independent.

Practice for this concept

Scope and references

Topics

Addition and multiplication rules, using complements

Learning goal

Apply probability rules after checking event relationships and conditions.

Helpful background

Check overlaps, conditions, and outcome counts.

Probability calculations

These choice exercises calculate or judge specified finite data, trials, or assumptions. They do not establish data collection, written inference, model validation, or mastery of the whole statistics area.

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