1. 12.1 – Inference for a Population Proportion

2. Conditions The data are an SRS from the population of interest The population is at least 10x sample Np, nq > 10

3. Z - Procedures An approximate level C confidence interval for p is: To test the hypothesis H o : p = p o, compute the z-statistic:

4. Example In the United States approximately 900 people die in bicycle accidents each year. One study examined the records of 1711 bicyclists aged 15 or older who were fatally injured in bicycle accidents between 1987 and 1991 and were tested for alcohol. Of these, 542 tested positive for alcohol (bac of 0.01% or higher) – Find a 95% confidence interval for p. – Test the claim that more than 1/3 of all bicycle accidents are alcohol-related.