Standard Deviation Calculator
Calculate the population standard deviation of three values. Standard deviation measures how spread out numbers are from the mean.
Écart type
8.164966
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.
- 01Mean = (10 + 20 + 30) / 3 = 20
- 02Squared differences: (10-20)² = 100, (20-20)² = 0, (30-20)² = 100
- 03Variance (population) = (100 + 0 + 100) / 3 = 66.6667
- 04Standard Deviation = √66.6667 ≈ 8.1650
Questions Fréquentes
What is standard deviation?
Standard deviation measures the amount of variation or dispersion in a data set. A low standard deviation means values are close to the mean; a high standard deviation means they are spread out.
What is the difference between population and sample standard deviation?
Population standard deviation divides by N (total count). Sample standard deviation divides by N-1 to correct for bias when estimating from a sample. Use sample when your data is a subset of a larger population.
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