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Math Help - Comparing Variances Question Help

  1. #1
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    Comparing Variances Question Help

    The McBurger company's management is interested in whether there is a difference in the standard deviation in services times for customers who use the drive-through window versus those who go inside to the service counter. A sample of 13 drive-through customers and a sample of 9 inside-counter customers were selected. The time (minutes) it took for each customer to be served was recorded. The following statistics are computed:
    Drive-through: mean = 4.5, s = 2.0
    Insider-counter: mean = 4.0, s = 1.2

    Based on a significance level of 0.10, determine if there is a difference in the standard deviation in service time.

    I'm assuming null hypothesis is var(drivethrough)/var(insider) = 1 and alternative hypothesis is var(drivethrough)/var(insider) /= 1, but I'm not sure of what to do after this. If anyone could post the steps I'll try to follow along, thanks!
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  2. #2
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    Re: Comparing Variances Question Help

    Quote Originally Posted by youngb11 View Post
    The McBurger company's management is interested in whether there is a difference in the standard deviation in services times for customers who use the drive-through window versus those who go inside to the service counter. A sample of 13 drive-through customers and a sample of 9 inside-counter customers were selected. The time (minutes) it took for each customer to be served was recorded. The following statistics are computed:
    Drive-through: mean = 4.5, s = 2.0
    Insider-counter: mean = 4.0, s = 1.2

    Based on a significance level of 0.10, determine if there is a difference in the standard deviation in service time.

    I'm assuming null hypothesis is var(drivethrough)/var(insider) = 1 and alternative hypothesis is var(drivethrough)/var(insider) /= 1, but I'm not sure of what to do after this. If anyone could post the steps I'll try to follow along, thanks!
    F or variance ratio test.

    1.3.5.9. F-Test for Equality of Two Standard Deviations

    CB
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