Standard Deviation Calculator
Calculate the mean, variance, and standard deviation of three numbers.
Mean
20.0000
Variance66.6667
Sample Std10.0000
Standard Deviation
Formula
Population SD = sqrt(sum of (xᵢ - mean)² / N)
Sample SD = sqrt(sum of (xᵢ - mean)² / (N-1))
Steps
1. Calculate the mean (average) 2. Find each value's deviation from the mean 3. Square each deviation 4. Average the squared deviations (divide by N for population, N-1 for sample) 5. Take the square root
Example Calculation
Find the standard deviation of 10, 20, 30.
- 01Mean = (10+20+30)/3 = 20
- 02Deviations: -10, 0, +10
- 03Squared: 100, 0, 100
- 04Variance = (100+0+100)/3 ≈ 66.67
- 05Std Dev = √66.67 ≈ 8.1650
Frequently Asked Questions
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