Blurb::
Aleatory uncertain discrete variable - negative binomial
Description::
 
The density function for the negative binomial distribution is given by: 
\f[f(x) = \left(\begin{array}{c}{n+x-1}\\{x}\end{array}\right){p^n}{(1-p)^{x}}\f] 
where 
- \f$p\f$ is the probability of success per trial 
- \f$n\f$ is the number of successful trials
- \f$X\f$ is the number of failures

Topics::	discrete_variables, aleatory_uncertain_variables
Examples::
Theory::
The negative binomial distribution is typically used to predict
the number of failures observed when repeating a test until a
total of \c n successes have occurred, where each test has a
probability \c p of success. 

Faq::
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