For a discrete random variable X with outcomes x₁, x₂, ..., xₙ and probabilities P(x₁), P(x₂), ..., P(xₙ):
E[X] = x₁ × P(x₁) + x₂ × P(x₂) + ... + xₙ × P(xₙ)
It is a weighted average: each outcome multiplied by its probability, then summed.
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$ curl repovive.com/roadmaps/math-fundamentals/probability-basics/expected-value-formula
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