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# Unit 9: Random variables

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## About this unit

Random variables can be any outcomes from some chance process, like how many heads will occur in a series of 20 flips of a coin. We calculate probabilities of random variables and calculate expected value for different types of random variables.

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- Constructing probability distributionsGet 3 of 4 questions to level up!
- Probability modelsGet 5 of 7 questions to level up!
- Probability with discrete random variablesGet 3 of 4 questions to level up!
- Expected valueGet 5 of 7 questions to level up!
- Mean (expected value) of a discrete random variableGet 3 of 4 questions to level up!
- Standard deviation of a discrete random variableGet 3 of 4 questions to level up!

### Practice

- Probability in density curvesGet 3 of 4 questions to level up!
- Probability in normal density curvesGet 3 of 4 questions to level up!

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- Combining random variablesGet 3 of 4 questions to level up!
- Combining normal random variablesGet 3 of 4 questions to level up!

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- Identifying binomial variablesGet 3 of 4 questions to level up!
- Binomial probability formulaGet 3 of 4 questions to level up!
- Calculating binomial probabilityGet 3 of 4 questions to level up!

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### Practice

- Mean and standard deviation of a binomial random variableGet 3 of 4 questions to level up!

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### Practice

- Binomial vs. geometric random variablesGet 3 of 4 questions to level up!
- Geometric probabilityGet 3 of 4 questions to level up!
- Cumulative geometric probabilityGet 3 of 4 questions to level up!

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### Practice

- Expected value with empirical probabilitiesGet 3 of 4 questions to level up!
- Expected value with calculated probabilitiesGet 3 of 4 questions to level up!
- Making decisions with expected valuesGet 3 of 4 questions to level up!

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