# Question: a A statistics practitioner calculated the mean and standard deviation

a. A statistics practitioner calculated the mean and standard deviation from a sample of 51. They are x̄ = 120 and s = 15. Estimate the population mean with 95% confidence.

b. Repeat part (a) with a 90% confidence level.

c. Repeat part (a) with an 80% confidence level.

d. What is the effect on the confidence interval estimate of decreasing the confidence level?

b. Repeat part (a) with a 90% confidence level.

c. Repeat part (a) with an 80% confidence level.

d. What is the effect on the confidence interval estimate of decreasing the confidence level?

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