Chapter 14 Interval Estimation / Confidence Intervals

The standard deviation of the sampling distribution is equal to -so we can reduce our formula above to: ± zα/2 . Example: If we have a sample of 49 children from a school and there are 9 of them with a cold. Find a 99% confidence interval for the true proportion of children at the school who have a cold. = 0.183. zα/2 = 2.576 = 0.0552 ................
................