Question 1055034: use a normal approximation to find the probability of the indicated scores, assume that n=100 and p=0.22
probability that x is at least 25
probability that x is exactly 19
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! use a normal approximation to find the probability of the indicated scores, assume that n=100 and p=0.22
probability that x is at least 25
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mean = n*p = 22
std = sqrt(22*0.78) = 4.14
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P(x >= 25) ~ P(x >= 24.5)
z(24.5) = (24.5-22)/4.14 = 0.60
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p(x >= 25) = P(z >= 0.6) = normalcdf(0.6,100) = 0.2743
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probability that x is exactly 19
P(x = 19) ~ P(18.5 <= x <= 19.5)
z(18.5) = (18.5-22)/4.14 = -0.85
z(19.5) = (19.5-22)/4.14 = 0.60
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P(x = 19) ~ P(-0.85<= z <= 0.6) = normalcdf(-0.85,0.6) = 0.5281
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Cheers,
Stan H.
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