If X1 X25 are a random sample from a normal population w

If X₁, · · · , X₂₅ are a random sample from a normal population with µ unknown and ² = 16, what is the 90% confidence interval for µ? If the sample variance S ² turns out to be 30, can we insist on the assumption that ² = 16? If not, what is the 90% confidence interval for µ?

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