Poisson Distribution CDF Calculator

Calculates the Poisson cumulative distribution function.

Formula: poisson(fcK, fcLam, 1)

See the Statistical Distributions Overview page for more statistical distribution calculators.

Example 1

For a Poisson distribution with a mean of 4, calculate the probability of P(X <= 8)

Value	Keystrokes	Display	Description
4.0	λ	4.0	Stores the λ value.
8	k	8.0	Stores the k value.
	cdf	0.9786	Calculates the cdf.

Example 2

Given that the number of customers arriving per hour at a business is a Poisson distribution, if the probability of 3 or fewer customers arriving is 0.5, what is the mean?

Value	Keystrokes	Display	Description
.5	cdf	0..5	Stores the cdf value.
3	k	3.0	Stores the k value.
	λ	3.672	Calculates the mean.

Reference:

Poisson distribution - Wikipedia