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Math Help - Find the margin error E

  1. #1
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    Find the margin error E

    Please help me solve this problem. I need to know what is the correct formula in order to solve the problem. Thanks

    Use the given confidence level and sample data to find (a) the margin error E and (b) a confidence interval for estimation the population mean u.

    Times between using a dishwasher: 90% confidence or 1.645 (critical value); n = 25, x = 5.24 sec, the population is normally distributed, and o is known to be 2.50 sec. Note: I was unable to put the minus sign over the x symbol.

    Sin
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  2. #2
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    Quote Originally Posted by sinlee2010
    Please help me solve this problem. I need to know what is the correct formula in order to solve the problem. Thanks

    Use the given confidence level and sample data to find (a) the margin error E and (b) a confidence interval for estimation the population mean u.

    Times between using a dishwasher: 90% confidence or 1.645 (critical value); n = 25, x = 5.24 sec, the population is normally distributed, and o is known to be 2.50 sec. Note: I was unable to put the minus sign over the x symbol.

    Sin
    For a sample of size N=25, we observe a mean \bar x = 5.24 \ sec.

    We know that the population is normally distributed with known standard
    deviation \sigma=2.5\ sec.

    Then 90% margin of error for the mean is:

    E= \frac{1.645 \frac{\sigma}{\sqrt N}}{\bar x}100\  \%\ \sim 15.67\  \%

    The 90% confidence interval is:

    (\bar x-1.645 \frac{\sigma}{\sqrt N},\bar x+1.645 \frac{\sigma}{\sqrt N})=(4.4275,6.0725).

    (Note that this retains more precision than is warranted)

    RonL
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  3. #3
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    Smile Find the Margin of Error

    Thanks for the help Captainblack......
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