SOLUTION: A standard placement test has a mean of 115 and a standard deviation of  = 10. Determine the minimum sample size if we want to be 90% certain that we are within 2 points of
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Question 323863: A standard placement test has a mean of 115 and a standard deviation of = 10. Determine the minimum sample size if we want to be 90% certain that we are within 2 points of the true mean Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! A standard placement test has a mean of 115 and a standard deviation of = 10. Determine the minimum sample size if we want to be 90% certain that we are within 2 points of the true mean
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Since E = zs/sqrt(n)
sqrt(n) = zs/E
n = [z*s/E]^2
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n = [1.645*10/2]^2
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n = 68 when rounded up
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Cheers,
Stan H.
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