(Solved): In a study of the effect of air pollution on lung function, a sample of 50 children living in a ...

In a study of the effect of air pollution on lung function, a sample of 50 children living in a community with a high level of ozone pollution had their lung capacities measured, and 14 of them had capacities that were below normal for their size. A second sample of 80 children was drawn from a community with a low level of ozone pollution, and 12 of them had lung capacities that were below normal for their size. A 95\% confidence interval for the difference in these proportions (high ozone low ozone) was constructed. Which of these is the width or length of the confidence interval? 0.294 0.290 0.121 0.277 0.147