A random sample of n measurements was selected from a population with unknown mean μ and s...

A random sample of n measurements was selected from a population with unknown mean μ and standard deviation σ = 20. Calculate a 95% confidence interval for μ for each of the following situations:

a.

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b.

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c.

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d.

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e. Is the assumption that the underlying population of measurements is normally distributed necessary to ensure the validity of the confidence intervals in parts a–d ?