# EXPONDIST

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Returns the exponential distribution. Use EXPONDIST to model the time between events, such as how long an automated bank teller takes to deliver cash. For example, you can use EXPONDIST to determine the probability that the process takes at most 1 minute.

**Syntax**

*EXPONDIST* ( **x** , *lambda* , *cumulative* )

**X** is the value of the function.

**Lambda** is the parameter value.

**Cumulative** is a logical value that indicates which form of the exponential function to provide. If cumulative is TRUE, EXPONDIST returns the cumulative distribution function; if FALSE, it returns the probability density function.

*Remarks*

If x or lambda is nonnumeric, EXPONDIST returns the #VALUE! error value.

If x < 0, EXPONDIST returns the #NUM! error value.

If lambda 0, EXPONDIST returns the #NUM! error value.

The equation for the probability density function is:

The equation for the cumulative distribution function is:

*Example 1*

Formula |
Description (Result) |
---|---|

=EXPONDIST(0.2,10,FALSE) |
Probability exponential distribution function (1.353353) |

*Example 2*

X |
Lambda |
Formula |
Description (Result) |
---|---|---|---|

0.2 |
10 |
=EXPONDIST([X,][Lambda],TRUE) |
Cumulative exponential distribution function (0.864665) |