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Math
Confidence Interval
CI for the mean (t≈z)
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Parameters
Results
- CI lower
- 39.566
- CI upper
- 45.434
- ± margin
- 2.934
- SE
- 1.4971
For small n, use the t-distribution; this uses a z approximation.
How it works
Build a confidence interval for a population mean.
Who it's for: Statistics students and researchers reporting estimate uncertainty.
CI = x̄ ± z·SE where SE = σ/√n.
Uses the supplied standard deviation (or sample s) and confidence level.
Approximates t with z for simplicity.
How to use
- Enter sample mean x̄, standard deviation σ (or s), sample size n, and confidence level.
- Read the lower and upper bounds of the interval.