# EXPONDIST function

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

The example may be easier to understand if you copy it to a blank worksheet.

• Create a blank workbook or worksheet.
• Select the example in the Help topic.

Note   Do not select the row or column headers.

Selecting an example from Help
• Press CTRL+C.
• In the worksheet, select cell A1, and press CTRL+V.
• To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.
A B
Data Description
0.2 Value of the function
10 Parameter value
Formula Description (Result)
=EXPONDIST(A2,A3,TRUE) Cumulative exponential distribution function (0.864665)
=EXPONDIST(0.2,10,FALSE) Probability exponential distribution function (1.353353)

Applies to:
Excel 2007