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Two Means - Sigma Known Hypothesis Test - Excel quiz

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  • When are you required to use a z-test instead of a t-test for comparing two means?
    You use a z-test when the population standard deviations (sigma1 and sigma2) are known.
  • What is the null hypothesis (H0) when testing two population means?
    The null hypothesis is that the two means are equal, or μ1 = μ2.
  • How do you express the alternative hypothesis if you suspect mean 1 is less than mean 2?
    The alternative hypothesis is μ1 < μ2.
  • What Excel function is used to calculate the sample mean from a data set?
    The AVERAGE function is used to calculate the sample mean.
  • What is the formula for the z-score in a two means, sigma known hypothesis test?
    The formula is z = (x̄1 − x̄2) / sqrt(σ1²/n1 + σ2²/n2).
  • How do you calculate the numerator for the z-score formula in Excel?
    Subtract the second sample mean from the first: =x̄1 - x̄2.
  • How do you calculate σ1²/n1 in Excel?
    Square sigma1, then divide by n1: =(sigma1^2)/n1.
  • Which Excel function is used to find the cumulative left-tail probability for a z-score?
    The NORM.S.DIST function with TRUE as the second argument is used.
  • What does it mean if your p-value is less than your significance level alpha?
    It means you reject the null hypothesis in favor of the alternative hypothesis.
  • In the example, what were the sample sizes for both groups?
    Both sample sizes were 30.
  • If the alternative hypothesis uses a less than symbol, which tail probability do you use?
    You use the left-tail probability.
  • What conclusion do you draw if the p-value is 0.04 and alpha is 0.05?
    You reject the null hypothesis because 0.04 < 0.05.
  • Why is it helpful to break the z-score formula into parts when using Excel?
    It reduces the chance of making calculation errors and makes the process easier.
  • What does rejecting the null hypothesis indicate in the context of the manufacturing example?
    It indicates there is enough evidence to conclude that machine A produces less on average than machine B.
  • What should you do if you want to practice more hypothesis tests for two means in Excel?
    You should check out additional examples provided in the lesson or course materials.