SOLUTION: Use the normal approximation to the binomial to find the probability for the specific value of X. n=30 p=0.5 X=18

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Question 1055176: Use the normal approximation to the binomial to find the probability for the specific value of X.
n=30 p=0.5 X=18
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
Binomial distribution P(x = 18) = binompdf(30, .5, 18) = .08
n=30 p=0.5
|Using the normal approximation to the binomial
mean = np = .5*30 = 15
variance = npq= 7.5
SD = √7.5 = 2.7386
P(x = 18) = normalpdf(18, 15, 2.785) = .0799
Found Using a Casio fx-115 ES plus
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For P(X=18) =P(X<18.5) - P(X<17.5)
=P (Z<(18.5-15)/√7.5) - P(Z<(17.5 -15)/√7.5)
P (z < 1.278) - P(z<.9129)
P(X=18) =0.8994 - 0.8194 =0.08