Confidence interval for a mean

Set the sample mean, standard deviation and size, and pick a confidence level, to see the interval.

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Questions students ask

What does a 95% confidence interval mean?

If you took many samples and built an interval from each, about 95% of them would contain the true mean.

What formula does it use?

x̄ ± z × σ/√n (z = 1.645, 1.96 or 2.576).

Free notes on confidence intervals

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