https://www.khanacademy.org/math/statistics-probability/random-variables-stats-library/random-variables-discrete/v/random-variables 2020-07-26T09:23:46Z Random variables Basic idea and definitions of random variables Sal Khan video https://cdn.kastatic.org/googleusercontent/qvRdke9M6v3Qpb1vuYZsEoZeINwGrsvcCs5yqZEV5wjs2Tq6BO4aQY1pMvIrKOTHrONu5sjnmgucCBokWEAt1MJ_ Random variables Basic idea and definitions of random variables https://cdn.kastatic.org/ka-youtube-converted/3v9w79NhsfI.mp4/3v9w79NhsfI.mp4 332 Random variable https://www.khanacademy.org/math/statistics-probability/random-variables-stats-library/random-variables-discrete/v/discrete-and-continuous-random-variables 2022-11-16T04:22:43.7414897Z Discrete and continuous random variables Discrete random variables can only take on a finite number of values. For example, the outcome of rolling a die is a discrete random variable, as it can only land on one of six possible numbers. Continuous random variables, on the other hand, can take on any value in a given interval. For example, the mass of an animal would be a continuous random variable, as it could theoretically be any non-negative number. Sal Khan video https://cdn.kastatic.org/googleusercontent/C-EUxA7o10ncTqWb2z3f09iyZER2yjTS385EnCOZNmur3MrWqHqiONcNUW0u6_lNg8yGeV8CPihpCspEs_uo-J5z Discrete and continuous random variables Discrete random variables can only take on a finite number of values. For example, the outcome of rolling a die is a discrete random variable, as it can only land on one of six possible numbers. Continuous random variables, on the other hand, can take on any value in a given interval. For example, the mass of an animal would be a continuous random variable, as it could theoretically be any non-negative number. https://cdn.kastatic.org/ka-youtube-converted/dOr0NKyD31Q.mp4/dOr0NKyD31Q.mp4 717 Random variable https://www.khanacademy.org/math/precalculus/x9e81a4f98389efdf:prob-comb/x9e81a4f98389efdf:expected-value/v/expected-value-of-a-discrete-random-variable 2022-10-07T00:22:18.752150461Z Mean (expected value) of a discrete random variable We can calculate the mean (or expected value) of a discrete random variable as the weighted average of all the outcomes of that random variable based on their probabilities. We interpret expected value as the predicted average outcome if we looked at that random variable over an infinite number of trials. video https://cdn.kastatic.org/ka_thumbnails_cache/74a42b52-15cb-443c-bd3d-cd165775c4c0_1280_720_base.png Mean (expected value) of a discrete random variable We can calculate the mean (or expected value) of a discrete random variable as the weighted average of all the outcomes of that random variable based on their probabilities. We interpret expected value as the predicted average outcome if we looked at that random variable over an infinite number of trials. https://cdn.kastatic.org/ka-youtube-converted/qafPcWNUiM8.mp4/qafPcWNUiM8.mp4 272 Random variable https://www.khanacademy.org/math/ap-statistics/random-variables-ap/xfb5d8e68:mean-standard-deviation-random-variables/v/variance-and-standard-deviation-of-a-discrete-random-variable 2024-01-19T18:34:27.70568811Z Variance and standard deviation of a discrete random variable We learn how to calculate the mean and standard deviation of a discrete random variable. The concept of a random variable is explained, along with methods to calculate its expected value (mean) and measure its spread (variance and standard deviation). A practical example makes the concept easier to understand. video https://cdn.kastatic.org/ka_thumbnails_cache/1480a2e2-c783-4cc6-b18d-f26efd6e3e77_1280_720_base.png Variance and standard deviation of a discrete random variable We learn how to calculate the mean and standard deviation of a discrete random variable. The concept of a random variable is explained, along with methods to calculate its expected value (mean) and measure its spread (variance and standard deviation). A practical example makes the concept easier to understand. https://cdn.kastatic.org/ka-youtube-converted/2egl_5c8i-g.mp4/2egl_5c8i-g.mp4 386 Random variable https://www.khanacademy.org/math/statistics-probability/random-variables-stats-library/random-variables-discrete/a/expected-value-basic 2021-04-29T07:58:49Z Expected value (basic) article https://www.khanacademy.org/math/precalculus/x9e81a4f98389efdf:prob-comb/x9e81a4f98389efdf:expected-value/e/mean-expected-value-discrete-random-variable 2026-03-25T22:11:09.709643949Z Mean (expected value) of a discrete random variable Practice calculating the mean of a discrete random variable. Jeff Dodds exercise https://www.khanacademy.org/math/ap-statistics/random-variables-ap/xfb5d8e68:mean-standard-deviation-random-variables/e/standard-deviation-discrete-random-variable 2021-07-01T02:19:28Z Standard deviation of a discrete random variable Practice calculating the standard deviation of a discrete random variable. Jeff Dodds exercise