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Math Help - confidence interval

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    Question confidence interval

    A 95% confidence interval for a population mean was reported to be 152 to 160. If = 15, what sample size was used in this study?
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    Quote Originally Posted by tonio77 View Post
    A 95% confidence interval for a population mean was reported to be 152 to 160. If = 15, what sample size was used in this study?
    Solve the following equations simultaneously for n:

    \bar{x} - \frac{1.96\sigma}{\sqrt{n}} = 152 .... (1)

    \bar{x} + \frac{1.96\sigma}{\sqrt{n}} = 160 .... (1)

    where \sigma = 15.
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