1. Topic 16 Example Confidence Intervals to Estimate a Population Proportion

2. AP Process 1.State the type of confidence interval you will be finding. 2.Check the requirements. State what they are, then check whether or not they are met. Also, mention what that means for your results. 3.State the formula using proper symbols. 4.Do the numerical substitution. 5.State the resulting confidence interval. 6.Make a statement interpreting this result in the context of the data.

3. Example Problem # 1 In a random sample of 400 people who were questioned regarding their participation in sports, 160 said that they did participate. Determine a 98% confidence interval for the proportion of people in the population who participate in sports.

4. Example Problem # 2 Determine the sample size necessary for a 95% confidence interval to have a margin-of- error of no more than 3%. Past studies (which were similar to this one) have resulted in a sample proportion of 25%.

5. Example Problem # 2 (continued) What would we do if we had no past study results?