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Expectation

Expectation is a probability-weighted average when defined; not every random variable has a finite expectation.

Different ways to understand it

The expectation of a continuous random variable | Teacher Changjiang
长江老师2210 · zh · Explanation
Connection evidence
Candidate from reviewed zh material v1: 数学期望按概率加权取值。若X有密度f且绝对可积，有限实数期望是xf(x)的积分。本站明确补充有密度与有限值的适用范围。
The expectation of a continuous random variable | Teacher Changjiang
长江老师2210 · zh · Explanation
Connection evidence
Candidate from reviewed en material v1: Expectation weights values by probabilities. For X with density f, finite real expectation is the integral of x f(x), provided the integral of absolute x times f(x) is finite. Density existence and finite-value scope are explicit editorial conditions.

LEARNING MAP

Move from uncertain events to random variables, probability models and evidence-based statistical inference.