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Standard deviation of n numbers with mean x̄:
AΣ(x - x̄)
BΣ x
Cmax - min
Dsqrt(Σ(x - x̄)² / n)
Answer & Solution
Correct answer: D. sqrt(Σ(x - x̄)² / n)
SD σ = sqrt(Σ(x_i - x̄)²/n). Measures spread around mean. Sample SD uses (n-1) instead. Variance = σ². Same units as data.
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