Geometric Distribution
A discrete random variable X is said to have a geometric distribution if it has a probability density function (p.d.f.) of the form:
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P(X = x) = q(x-1)p, where q = 1 - p
If X has a geometric distribution with parameter p, we write X ~ Geo(p)
Expectation and Variance
If X ~ Geo(p), then:
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E(X) = 1/p
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Var(X) = q/p2, where q = 1 – p
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