Revision as of 06:54, 3 November 2008 by Kpekkari (Talk)

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the variance of a binomial random variable:

  • var(X) = E[X^2] - (E[X])^2
  • = E[X(X-1)] + E[X] - (E[X])^2
  • = n*(n-1)*P^2 + n*p - (n*p)^2
  • = n*p - n*p^2
  • now, set n = 1000, take derivative with respect to p, set equal to zero, solve for p, and plug into var(x) equation to solve for the maximum value.
  • i end up getting p = .5 so max var(X) = 250 (when X is a binomial random variable with parameter 1000)

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