Question 887937: How large a sample size is needed to estimate the mean annual income of people in a certain country, correct to within $800 with probability 0.99? No information is available about the standard deviation of their income. It is estimated that nearly all of the incomes fall between $0 and $180,000 and that this distribution is approximately bell-shaped.
n =
(round up to the nearest integer)
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! How large a sample size is needed to estimate the mean annual income of people in a certain country, correct to within $800 with probability 0.99? No information is available about the standard deviation of their income. It is estimated that nearly all of the incomes fall between $0 and $180,000 and that this distribution is approximately bell-shaped.
n =[z*s/E]^2
Comment: When sigma is not given 6*s = range of the data = 180,000
s = 180,000/6 = 30,000
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n = [2.5758*30,000/800]^2 = 9331 (rounded up to the nearest integer)
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Cheers,
Stan H.
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