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An economist is asked to estimate the average duration of unemployment (measured in months) in a...

An economist is asked to estimate the average duration of unemployment (measured in months) in a population. From a random sample of 9 spells of unemployment, she finds a sample average duration of 8. Suppose that she knows the population standard deviation of spells is σ = 3.

(a) Find a 90% confidence interval for the population average duration. (b)TestH0 : μ=7againstHA : μ>7withα=0.05.

(c) If the true (but unknown) average duration is in fact μ = 8 then what is the power of the test in part (b)?

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Answer #1

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