Calculatrice d'Écart-type — Formule

How to Calculate Standard Deviation

Formula (Population)

σ = √[ Σ(xᵢ - μ)² / N ]

Steps

1. Find the mean (μ) of the data set 2. Subtract the mean from each value and square the result 3. Find the average of those squared differences 4. Take the square root

For a sample standard deviation, divide by (N-1) instead of N.

Exemple Résolu

Find the standard deviation of 10, 20, and 30.

  1. Mean = (10 + 20 + 30) / 3 = 20
  2. Squared differences: (10-20)² = 100, (20-20)² = 0, (30-20)² = 100
  3. Variance (population) = (100 + 0 + 100) / 3 = 66.6667
  4. Standard Deviation = √66.6667 ≈ 8.1650