Airlines. An airline company would like to compare two different routes from Paris to New York. Flights are randomly assigned to two different routes. Thirty f lights following Route A report an average of 466 minutes, with a standard deviation of 15 minutes. Thirty f lights following Route B report an average of 475 minutes, with a standard deviation of 11 minutes. Histograms of travel times for the routes are roughly symmetric and show no outliers.

a) Find a 95% confidence interval for the difference in average time for the two routes.

b) Which route is better? Explain.