Confidence Interval Calculator
The confidence interval for a mean: mean ± z·(SD/√n).
Result
Margin of error
5.37
Lower bound
94.63
Upper bound
105.37
How it works
CI = mean ± z · (SD ÷ √n)
A confidence interval is the range likely to contain the true mean. A 95% interval means that, over many samples, 95% of such intervals would capture the real value.
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Frequently asked questions
What does 95% confidence mean?
If you repeated the sampling many times, about 95% of the intervals would contain the true mean.
How do I narrow the interval?
Increase the sample size or lower the confidence level — both shrink the margin of error.
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