Statistics
Class 11

Standard Deviation

σ=(xixˉ)2n\sigma = \sqrt{\frac{\sum(x_i - \bar{x})^2}{n}}
02040608010000.0050.010.0150.020.0250.030.0350.04
σ = √[Σ(xᵢ-x̄)²/n]

Adjust Variables

Mean μ
mu =
0100
Std Dev σ
sigma =
130

Measures spread of data around the mean. Low σ = data clustered near mean; high σ = data spread out.

Real-World Applications

Finance — Stock volatility is standard deviation of returns.

Quality control — Six Sigma = process within 6σ of target.

Weather — Temperature variability across seasons.

Sports — Consistency of player performance.

Medicine — Variability in patient vital signs.

Manufacturing — Tolerance limits: mean ± 3σ.

Education — Spread of test scores.

Polling — Margin of error based on σ.

Psychology — IQ distribution (mean=100, σ=15).

Insurance — Risk assessment through claim variability.

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