N
Normal Distribution Calculator
The probability of a value below, above or between points on a normal curve.
Result…
How it's calculated
z = (x − μ) ÷ σ P(X < x) = Φ(z) P(a < X < b) = Φ(z_b) − Φ(z_a)
Many measurements (heights, test scores, measurement errors) are close to normally distributed. About 68% of values fall within one standard deviation of the mean, 95% within two and 99.7% within three. Φ is computed from the error function to about 12 significant digits.
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