Environment, part 2.

Consider again the relationship between the population and ozone level of U.S. cities that you analyzed in Exercise 61.

a) Give a 90% confidence interval for the approximate increase in Ozone level associated with each additional million city inhabitants.

b) For the cities studied, the mean population was 1.7 million people. The population of Boston is approximately 0.6 million people. Predict the mean ozone level for cities of that size with an interval in which you have 90% confidence.