# Manuals/calci/EXPONDIST

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**EXPONDIST(X,Lambda,Cumulative)**

- is the value of the function.
- is the value of the rate parameter.
- is the logical value like TRUE or FALSE.
- EXPONDIST(), returns the exponential distribution.

## Description

- This function gives the Exponential Distribution. This distribution is used to model the time until something happens in the process.
- This describes the time between events in a Poisson process i.e, a process in which events occur continuously and independently at a constant average rate.
- For e.g Time between successive vehicles arrivals at a workshop.
- Exponential distribution is the only continuous memoryless random distribution. It is a continuous analog of the Geometric distribution.
- In , is the value of the function, is called rate parameter and is either TRUE or FALSE.
- This function will give the Cumulative Distribution Function when is TRUE, otherwise it will give the Probability Density Function , when is FALSE.
- Suppose we are not giving the value, by default it will consider the value is FALSE.
- This function will give the error result when

1. or is non-numeric. 2. or

The Probability Density Function of an Exponential Distribution is: or

- where is the rate parameter and is the Heaviside step function
- This function is valid only on the interval [0,infinity].

The Cumulative Distribution Function is : or

## ZOS

- The syntax is to calculate EXPONDIST in ZOS is .
- where is the value of the function
- is the value of the rate parameter
- is the logical value like TRUE or FALSE.

- For e.g.,EXPONDIST(11..12,2.3..3.3..0.4,FALSE)

## Examples

Question : If jobs arrive at an average of 15 seconds, per minute, what is the probability of waiting 30 seconds, i.e 0.5 min? Here and

- =EXPONDIST(0.5,5,TRUE) = 0.917915001
- =EXPONDIST(5,3,TRUE) = 0.999999694
- =EXPONDIST(0.4,2,FALSE) = 0.898657928

## Related Videos

## See Also

## References