Luis A. Afonso
Posts:
4,758
From:
LIsbon (Portugal)
Registered:
2/16/05
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Re: Help with probability&stat problem
Posted:
Jun 12, 2007 2:43 AM
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My response
I answered, strictly, what the OP asked: to use the normal approximation to evaluate a binomial problem, NOT what where the different procedures to do it, or what was the best one.
The formula to find APPROXIMATELLY p(X<=a) is
______ z = (a + 0.5 - p*N) / s
______ s^2 = p * (1-p) * N
and p(X<=a) = F(z) , the Normal Standard DF at the point z, X~ Binomial (p, N), p the constant probability of success at each Bernouilli N trials.
This method is called currently the CLASSICAL CONTINUITY APPROXIMATION, a standard method that was indicated yet in this thread.
Jack Tomsky did not take into account. HE DIDN`T PAY ATTENTION (!).
Licas
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