A Random Sample of 80 Observations Produced a Mean $\bar { x } = 35.4 \text { and a standard deviation } s = 3.1 \text {. }$

A random sample of 80 observations produced a mean $\bar { x } = 35.4 \text { and a standard deviation } s = 3.1 \text {. }$ a. Find a 90% confidence interval for the population mean μ. b. Find a 95% confidence interval for μ. c. Find a 99% confidence interval for μ. d. What happens to the width of a confidence interval as the value of the confidence coefficient is increased while the sample size is held fixed? 7.3 Confidence Interval for a Population Mean: Student's t-Statistic 1 Compare t-Distribution to Normal Distribution