# The Excel PROB Function

## Function Description

Given a list of values and a corresponding list of probabilities, the Excel PROB function calculates the probability associated with a given range.

The syntax of the function is:

PROB( x_range, prob_range, [lower_limit], [upper_limit] )

where the function arguments are as follows:

 x_range - An array of values that have associated probabilities. prob_range - The array of probabilities corresponding to the values in x_range.(This array must have the same length as the x_range array and the values in prob_range must add up to 1). lower_limit - The lower bound of the range of values for which you want to calculate the probability. [upper_limit] - An optional value that denotes the upper bound of the range that you want to calculate the probability for.(If the [upper_limit] is omitted, the function simply returns the probability associated with the value of the supplied lower_limit).

## Prob Function Examples

Columns A and B of the spreadsheet below contain a set of values and their associated probabilities. These values and probabilities are provided to the Excel Prob functions in cells C1-C3 of the spreadsheet.

ABCD
1xprobability=PROB( A2:A9, B2:B9, 3 ) - Returns the value 0.22
200.1=PROB( A2:A9, B2:B9, 3, 5 ) - Returns the value 0.52
310.15=PROB( A2:A9, B2:B9, 8, 10 ) - Returns the value 0
420.17
530.22
640.21
750.09
860.05
970.01

For further details and examples of the Excel Prob function, see the Microsoft Office website.

## Prob Function Errors

If you get an error returned from the Excel Prob Function, this is likely to be one of the following:

Common Errors
 #NUM! - Occurs if either:Any value in the supplied prob_range is <0 or >1orThe values in the supplied prob_range do not add up to 1. #N/A! - Occurs if the supplied x_range and prob_range arrays are of different lengths (i.e. contain different numbers of data points).