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# Normal Distribution CDF Upper Tail Calculator

Calculates the normal distribution cumulative distribution function for the upper tail. The cumulative normal distribution function describes probabilities for a random variable to fall in the intervals of the form (x, ∞].

Formula: 1-normdist(x0, mn, sd, 1)

## Example 1

If the mean speed of the vehicles on a road is 60 and the standard deviation is 4, what percent are going over 65?

Value Keystrokes Display Description
65 x 65.0000 Stores the x value.
60 μ 60.0000 Stores the mn (mean) value.
4 σ 4.0000 Stores the sd (standard deviation) value.
cdf 0.1056 Calculates the cumulative distribution function.

## Example 2, Inverse

What speed are 0.05 of the vehicles going over?

These keystrokes assume the values from example 1.

Value Keystrokes Display Description
.05 cdf 0.050 Stores the cdf value.
x 66.58 Calculates the x (inverse) value.

To calculate the standard values forund in tables, use μ = 0 and σ = 1.

Reference:

Normal distribution - Wikipedia