NEGBINOMDIST

NEGBINOMDIST(number_f, number_s, probability_s)

Returns the probability distribution function for a negative binomial distribution (no cumulative).

number_f	The number of failures.
number_s	The threshold number of successes.
probability_s	The probability of a success.

REMARKS

* This function is only available for backwards compatibility and should not be used.
* NEGBINOM.DIST was added in Excel 2010 to replace this function and include an option for cumulative probability.
* The negative binomial distribution is a discrete distribution
* This function returns the probability that there will be "number_f" failures before the "number_s"-th success, when the constant probability of a success is "probability_s".
* For example, you need to find 10 people with excellent reflexes, and you know the probability that a candidate has these qualifications is 0.3.
* This function calculates the probability that you will interview a certain number of unqualified candidates before finding all 10 qualified candidates.
* The "number_f" and "number_s" are truncated to integers.
* If any of the arguments are not numeric, then #VALUE! is returned
* If "probability_s" < 0, then #NUM! is returned.
* If "probability_s" > 1, then #NUM! is returned.
* If ("number_f" + "number_s" - 1) = 0, then #NUM! is returned.
* The equation for the negative binomial distribution is: ??
* For the Microsoft documentation refer to support.microsoft.com
* For the Google documentation refer to support.google.com

	A
1	=NEGBINOMDIST(0, 1, 0.25) = 0.25
2	=NEGBINOMDIST(0, 1, 0.5) = 0.5
3	=NEGBINOMDIST(1, 6, 0.5) = 0.047
4	=NEGBINOMDIST(10, 5, 0.25) = 0.055
5	=NEGBINOMDIST(10, 5, -4) = #NUM!
6	=NEGBINOMDIST(10, "some text", 0.25) = #VALUE!