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Stat: estimate proportion

  1. Dec 6, 2008 #1
    1. The problem statement, all variables and given/known data
    A candidate wishes to estimate the proportion, among likely voters who would vote for her on election day, with 80% margin of error less than 0.03. What sample size should she use?
    Answer: 456

    2. Relevant equations
    +/- Z[phat*qhat/sqrt(n)], Z = 1.28, phat = 0.5, qhat = 0.5


    3. The attempt at a solution

    0.03 = 1.28 sqrt[0.5*0.5/n]
    0.03/1.28 = 0.5/sqrt(n)
    0.0234 = 0.5/sqrt(n)
    n = [0.5/0.0234]^2
    n = 456

    Is the above correct. It matches with the answer 456. I don't know how to delete this question.
     
    Last edited: Dec 6, 2008
  2. jcsd
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