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Homework Help: Statistics, sample size determination

  1. Jul 17, 2011 #1
    1. The problem statement, all variables and given/known data
    Glucose level is normally distributed, standard deviation is known to be 25 units; determine the sample size needed to be 95% confident that the sample mean and the true population mean differ by at most 4 units.

    2. Relevant equations
    (work shown below)

    3. The attempt at a solution
    Margin of error = 4 units
    Margin of error = z * standard error
    4=1.96 * (25/(n)^1/2)
    4 = (49) / (n)^1/2
    49 = 4(n)^1/2
    (12.25)^2 = (n^1/2)^2
  2. jcsd
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