Normal Distribution Calculator
Cumulative Probability P(Z ≤ z)
Formula
P(Z ≤ z) using Abramowitz & Stegun rational approximation
Frequently Asked Questions
What is the standard normal distribution?
The standard normal distribution is a bell-shaped curve with a mean of 0 and standard deviation of 1. About 68% of values fall within ±1 SD, 95% within ±2 SD, and 99.7% within ±3 SD.
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