Chapter 9, Problem 34SE

Confidence Interval Changes State whether each of the following changes would make a confidence interval wider or narrower. (Assume that nothing else changes.)

a. Changing from a $95\%$ level of confidence to a $90\%$ level of confidence

b. Changing from a sample size of 30 to a sample size of 20

c. Changing from a standard deviation of 3 inches to a standard deviation of $2.5$ inches