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# Unit 11: Confidence intervals

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## About this unit

"The average lifespan of a fruit fly is between 1 day and 10 years" is an example of a confidence interval, but it's not a very useful one. From scientific measures to election predictions, confidence intervals give us a range of plausible values for some unknown value based on results from a sample. Let's learn to make useful and reliable confidence intervals for means and proportions.

### Learn

### Practice

- Conditions for a z interval for a proportionGet 3 of 4 questions to level up!
- Finding the critical value z* for a desired confidence levelGet 3 of 4 questions to level up!
- Calculating a z interval for a proportionGet 3 of 4 questions to level up!
- Sample size and margin of error in a z interval for pGet 3 of 4 questions to level up!

### Learn

### Practice

- Conditions for a t interval for a meanGet 3 of 4 questions to level up!
- Finding the critical value t* for a desired confidence levelGet 3 of 4 questions to level up!
- Calculating a t interval for a meanGet 3 of 4 questions to level up!
- Sample size and margin of error in a confidence interval for a meanGet 3 of 4 questions to level up!

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