A statistics practitioner selected a random sample of 75 observations from a population with a known standard deviation equal to 15 and computed a sample mean equal to 90. a) Estimate the population mean with 95% confidence. b) Repeat Part a) using a 98% level of confidence. c) Repeat Part a) using a population standard deviation equal to 20. d) Repeat Part a) using a sample size equal to 400. Any changes to C.I.?

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