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Math Help - Finding Confidence Intervals for Mean, Variance, and Standard Deviation

  1. #1
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    Finding Confidence Intervals for Mean, Variance, and Standard Deviation

    I really need some help with this problem ASAP. Here is the problem word-for-word:
    Find the 90% confidence interval for the mean, variance, and standard deviation for the price in dollars of an adult single-day lift ticket. The data represent a selected sample of nationwide ski resorts. Assume the variable is normally distributed.

    $59 $54 $53 $52 $51
    $39 $49 $46 $49 $48

    Thanks in advance for your help!
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  2. #2
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    Re: Finding Confidence Intervals for Mean, Variance, and Standard Deviation

    Hi there, let's do these one at a time so you fully understand.

    Your data is normal, but you don't know the population standard deviation

    Therefore the confidence interval for the mean is \displaystyle \bar{x}\pm t_{1-\frac{\alpha}{2}, n-1}\times\frac{s}{\sqrt{n}}

    Where

    n is the number of samples

    \bar{x} is the sample mean

    s is the sample standard deviation

    t is the test statistic, and

    \alpha is the level of significance

    What do you get?
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