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Explore the fundamentals of random variables, including discrete and continuous types. Learn about probability mass functions for discrete variables and probability density functions for continuous variables, along with how to calculate expected value and variance. Delve into various probability distributions, including Poisson, Exponential, Uniform, Triangular, and Normal distributions. Understand how these distributions apply to real-world scenarios, such as random arrivals and manufacturing, and the significance of the Central Limit Theorem.
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Random Variable 2013
Random Variable • Two types • Discrete • Continuous
Random Variable • Probability mass function • Discrete • P(X = xi) = p(xi) • p(xi) = 1
Random Variable • Probability density function • Continuous • f(x) = e –x x > 0 • P(X = a) = 0 • - f(x) dx = 1 • P(a < x < b) = ab f(x) dx
Random Variable • Expected value • = E(x) • = xi p (xi) • = x f(x) dx
Random Variable • Variance
Random Variable • Standard deviation • Sums of R.V.
The Triangular Distribution • Continuous Distribution
Selecting a Distribution • Theoretical prior knowledge • Random arrival => exponential IAT • Sum of large manufactures => Normal CLT • Compare histogram with probability mass or probability density