# EXPON.DIST

The EXPON.DIST function returns the exponential distribution of a specified random variable, x, given a specified lambda, LAMBDA. The exponential distribution is commonly used to model the time between events in a Poisson process. The function returns the probability density function or the cumulative distribution function of the exponential distribution depending on whether the cumulative argument is set to TRUE or FALSE. This function is useful for analyzing reliability data and can be used to determine the probability that a component will fail before a certain time.

## Usage

Use the `EXPON.DIST` formula with the syntax shown below, it has 3 required parameters:

Parameters:
1. x (required):
The value of the random variable at which to evaluate the distribution.
2. LAMBDA (required):
The parameter of the exponential distribution which represents the average value of the distribution.
3. cumulative (required):
A logical value that determines whether to return the probability density function or the cumulative distribution function. If TRUE, returns the cumulative distribution function; if FALSE, returns the probability density function.

## Examples

Here are a few example use cases that explain how to use the `EXPON.DIST` formula in Google Sheets.

### Calculating the probability of an event occurring within a certain time period

By using the EXPON.DIST function, you can calculate the probability that an event will occur before a certain time period based on the average time between events. For example, if the average time between failures for a component is 100 hours, you can use the function to calculate the probability that the component will fail within the next 50 hours.

### Modeling the time between events in a Poisson process

The exponential distribution is commonly used to model the time between events in a Poisson process. The EXPON.DIST function can be used to calculate the probability that a certain amount of time will pass between events based on the average time between events.

### Analyzing reliability data

The exponential distribution is often used to model the failure times of components in a system. By using the EXPON.DIST function, you can analyze the reliability of a system and determine the probability that a component will fail before a certain time period.

## Common Mistakes

`EXPON.DIST` not working? Here are some common mistakes people make when using the `EXPON.DIST` Google Sheets Formula:

### Incorrect order of arguments

One common mistake is to input the arguments in the wrong order. The correct order is: x, LAMBDA, cumulative.

### Invalid input type

The x and LAMBDA arguments must be numeric values. If you input non-numeric values, the formula will return an error.

### Incorrect range for arguments

Make sure that the x and LAMBDA values are within the expected range for your intended use of the formula. If they are not, the result may not be what you expect.

### Confusion with cumulative argument

The cumulative argument can be either TRUE or FALSE. If you input TRUE, the formula returns the cumulative distribution function; if you input FALSE, it returns the probability density function. Make sure you understand which one you need for your intended use of the formula.

### Missing arguments

Make sure that you include all three required arguments for the formula: x, LAMBDA, and cumulative. If you omit one or more arguments, the formula will return an error.

The following functions are similar to `EXPON.DIST` or are often used with it in a formula:

• `EXPONDIST`

The `EXPONDIST` function calculates the probability of an event occurring at a specific time, assuming that the events follow an exponential distribution. It is commonly used in reliability analysis to model the time between failures of a system.

• `GAMMADIST`

The GAMMADIST function calculates the gamma distribution for a given set of parameters. The gamma distribution is a continuous probability distribution that is often used in statistics. It is commonly used to model the time between events. The function returns the probability density function or the cumulative distribution function for a given set of parameters.

• `NORMDIST`

The `NORMDIST` function in Google Sheets calculates the normal distribution for a specified value, mean, and standard deviation. It returns the probability of a value occurring within a specified range of a normal distribution. It is commonly used in statistics, finance, and science to analyze data and make predictions.

You can learn more about the `EXPON.DIST` Google Sheets function on Google Support.