| Confidence Interval for Population Proportion | | Notes |
| Number of successes in sample | 421 |
| Sample size, n | 500 |
| confidence level, c | 0.95 |
| sample proportion, p | 0.842 | Number of successes/sample size |
| critical z value, z | 1.9599639845 | Uses the NORMSINV function in excel; NORMSINV((1+c)/2) |
| standard error, SE | 0.0163117136 | SQRT(p*(1-p)/n) |
| margin of error, MOE | 0.0319703711 | z * SE |
| lower confidence limit | 0.8100296289 | p - MOE |
| upper confidence limit | 0.8739703711 | p + MOE |
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| Enter data highlighted in yellow. Rows 5 through 10 are calcualted using data from rows 2 through 4. |