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Confidence Intervals for Population Means - Excel quiz

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  • What two values do you need to construct a confidence interval for a population mean?
    You need the sample mean (x̄) and the margin of error (e).
  • What are the formulas for the lower and upper bounds of a confidence interval for a mean?
    The lower bound is x̄ - e and the upper bound is x̄ + e.
  • Which Excel function is used to find the sample mean?
    The =AVERAGE function is used to find the sample mean.
  • When the population standard deviation (σ) is known, which Excel function is used to find the margin of error?
    Use the =CONFIDENCE.NORM function to find the margin of error when σ is known.
  • What are the three required inputs for the CONFIDENCE.NORM function in Excel?
    The inputs are alpha, sigma (population standard deviation), and n (sample size).
  • How do you calculate alpha for a confidence interval in Excel?
    Alpha is calculated as 1 minus the confidence level (e.g., =1-0.99 for a 99% confidence level).
  • If the population standard deviation is unknown, which Excel function should you use to find the margin of error?
    Use the =CONFIDENCE.T function when the population standard deviation is unknown.
  • What value replaces sigma in the CONFIDENCE.T function when sigma is unknown?
    The sample standard deviation (s) replaces sigma in the CONFIDENCE.T function.
  • Which Excel function is used to calculate the sample standard deviation?
    The =STDEV function is used to calculate the sample standard deviation.
  • What is the general process for constructing a confidence interval in Excel?
    Find the sample mean, calculate the margin of error, then compute the lower and upper bounds using x̄ ± e.
  • How do you calculate the lower bound of a confidence interval in Excel?
    Subtract the margin of error from the sample mean (e.g., =x̄ - e).
  • How do you calculate the upper bound of a confidence interval in Excel?
    Add the margin of error to the sample mean (e.g., =x̄ + e).
  • What does a 99% confidence interval mean in the context of a population mean?
    It means you are 99% confident that the true population mean lies within the calculated interval.
  • What does a 95% confidence interval indicate about the population mean?
    It indicates you are 95% confident that the true population mean is within the interval's bounds.
  • Why is the t-distribution used instead of the normal distribution when sigma is unknown?
    The t-distribution accounts for the extra uncertainty from estimating the population standard deviation with the sample standard deviation.