# NEGBINOMDIST

Formulas / NEGBINOMDIST
Calculate the probability of an event occurring given that the event has a specific number of chances of occurring.
`=NEGBINOMDIST(number_of_successes,trials,probability_of_success,cumulative)`
• number_f - the number of failures before success
• number_s - the required number of successes
• probability_s - the probability of success in a single trial

## Examples

• `=NEGBINOMDIST(3, 5, 0.4)`

In this example, the NEGBINOMDIST function is used to calculate the probability of getting the third failure on the fifth trial in a series of independent Bernoulli trials, where the probability of failure on each trial is 0.4. The formula returns the probability of this event occurring, which is approximately 0.13824.

• `=NEGBINOMDIST(2, 7, 0.3)`

In this example, the NEGBINOMDIST function is used to calculate the probability of getting the second failure on the seventh trial in a series of independent Bernoulli trials, where the probability of failure on each trial is 0.3. The formula returns the probability of this event occurring, which is approximately 0.18522.

## Summary

The NEGBINOMDIST function is used to determine the probability of an event occurring at least once. It takes four inputs, including the probability of the event occurring and the number of successes and chances. The function returns the probability of the event occurring at least once.

• The NEGBINOMDIST function takes three inputs: the probability of the event occurring, the number of times the event can occur, and the probability of the event occurring at least once.
• The probability of the event occurring and the number of times the event can occur must be expressed as decimals.
• The NEGBINOMDIST function calculates the probability of the event occurring at least once, not the probability of the event occurring a specific number of times.