Experience 9 - Confidence Intervals for the Mean

Confidence Intervals for the Mean



Recall that one of our original goals was to use a sample mean to estimate  a population mean. We will now formulate the error for this estimation and we can then make scientific arguments regarding the range of values that a population mean can take on. This will show how the sample size, spread, and confidence of an estimate all play an important role in estimation. Finally you will know enough to validate the statistical claims made by others about population means. 

Learning Objectives

  • Know how to determine and interpret a confidence interval for the mean
  • Understand the roles of sample size, confidence level, and spread on the margin of error.

Performance Criteria

  • The learner will calculate confidence intervals for the mean using technology accurate to 2 decimal places.
  • The learner will interpret confidence intervals for the mean using a complete sentence that includes the units of the random variable and the confidence level.
  • The learner will determine the sample size necessary for a desired margin of error.

Discover Confidence Intervals

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Chapter 8 (This is a video by the authors covering chapter 8. Just watch the parts relating to sections 8.1-8.2)

Confidence Intervals for the Mean (TI-84)

Confidence Intervals for the Mean (Excel)

Click on "Textbook" to view the assigned reading or read Sections 8.1-8.2 from your print or digital copy.

The main site will calculate using summary stats and find sample size.

Alternate Calculator:

CI calculator that takes sample data

If you can find a better site please send me the link


  1. Review - Read the above components and post any questions in the forum below. 
  2. Practice - Complete the practice exercises that follow.
  3. Think - Answer the Critical Thinking questions in the "Critical Thinking" forum. 
  4. Apply - Complete the Application Problems and upload your completed file
  5. Assess - Complete the Peer Assessment for this Experience.

If you have any questions about the content (readings, problems, etc.) then post in the "Questions about Experience 9" forum. 

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Practice Problem Videos

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