Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

Exercise 14

Confidence Intervals: Sample Size A random sample is drawn from a population with = 12. The sample mean is 30.
(a) Compute a 95% confidence interval for based on a sample of size 49. What is the value of the margin of error
(b) Compute a 95% confidence interval for based on a sample of size 100. What is the value of the margin of error
(c) Compute a 95% confidence interval for based on a sample of size 225. What is the value of the margin of error
(d) Compare the margins of error for parts (a) through (c). As the sample size increases, does the margin of error decrease
(e) Critical Thinking Compare the lengths of the confidence intervals for parts (a) through (c). As the sample size increases, does the length of a 90% confidence interval decrease