# Confidence Intervals: Sample Size A random sample is drawn from a population with σ = 12. The sample mean is 30. (a) Compute a 95% confidence interval for µ based on a sample of size 49. What is the value of the margin of error? (b) Compute a 95% confidence interval for µ based on a sample of size 100. What is the value of the margin of error? (c) Compute a 95% confidence interval for µ 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?

### Understanding Basic Statistics

8th Edition
Charles Henry Brase + 1 other
Publisher: Cengage Learning
ISBN: 9781337558075

### Understanding Basic Statistics

8th Edition
Charles Henry Brase + 1 other
Publisher: Cengage Learning
ISBN: 9781337558075

#### Solutions

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Section
Chapter 8.1, Problem 21P
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