Geometric distribution
The geometric distribution is a discrete probability distribution that describes the probability that a Bernoulli process will have its first success on the nth trial if the probability of success is p:
It has mean and variance
It is a special case of the negative binomial distribution where r = 1. Like its continuous analogue (the exponential distribution), the geometric distribution is "memoryless"; in fact, it is the only memoryless discrete distribution.
Until somebody adds more information, please refer to negative binomial distribution.
