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Confidence Interval Calculator

Calculate confidence intervals for proportions and means at 90%, 95%, or 99% confidence levels.

Z-score: 1.96

Results

Lower Bound

0.4690

Margin of Error

Âą0.0310

Upper Bound

0.5310

0.46900.5310

We are 95% confident that the true proportion is between 0.4690 and 0.5310.

Formula

p Âą z × √(p(1-p)/n) = 0.5 Âą 1.96 × √(0.5×0.5000/1000)

Z-Score Reference

Confidence LevelZ-Score
90%1.645
95%1.96
99%2.576