Chapter 8.3, Problem 123E

In each of Exercises 8.123–8.128, we provide a sample mean, sample size, sample standard deviation, and confidence level. In each exercise,

1. a. use the one-mean t-interval procedure to find a confidence interval for the mean of the population from which the sample was drawn.
2. b. obtain the margin of error by taking half the length of the confidence interval.
3. c. obtain the margin of error by using the formula $t_{\alpha /2}\cdot s/\sqrt{n}$.

8.123 $\bar{x}$ = 20, n = 36, s = 3, confidence level = 95%