Suppose that X1,...,Xr are independent random variables,
Chapter 3, Problem 3.2.4(choose chapter or problem)
Suppose that X1,...,Xr are independent random variables, each with a geometric distribution with parameter p. Explain why Y = X1 ++Xr has a negative binomial distribution with parameters p and r. Use this relationship to establish the mean and variance of a negative binomial distribution.
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