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The mean of a probability distribution is defined using the symbol μ and the formula μ = Σ x P(x). What role does this μ play for a discrete random variable?
AThe single most frequent outcome in one trial
BThe long-term average outcome of repeated trials
CThe largest x value the variable can take
DThe number of distinct outcomes in the table
Answer & Solution
Correct answer: B. The long-term average outcome of repeated trials
1. The glossary defines the mean of a probability distribution directly.
2. It is the long-term average outcome that emerges after many repeated trials of the experiment.
3. Option B restates that definition correctly.
4. Options A, C, and D each describe a different feature of the table, none of which is what μ measures.
_Source: OpenStax Introductory Statistics (CC BY 4.0), Ch 4 "Discrete Random Variables", section 4.2 Mean or Expected Value and Standard Deviation_
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