Confidence Intervals
A sample mean is only an estimate. A confidence interval gives a range likely to contain the true mean. A 95% interval is mean ± t * standard error, where t comes from the t-distribution (used because the true standard deviation is unknown). Wider samples give narrower intervals.
The 95% refers to the method: if you repeated the study many times, about 95% of such intervals would contain the true mean.
Examplepython
Quick check
Collecting a bigger sample usually makes a confidence interval...
Your turn: write the code
Print the lower end of the 95% confidence interval for the mean, rounded to 2 decimals.
Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.
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