An ambulance service located at the edge of town is responsible for serving a large office building in the downtown area. Testing different routes for getting from the ambulance station to the office building, a driver finds that five trips using route A take an average of 5.9 minutes, with a standard deviation of 1.4 minutes; six trips using route B take an average of 4.2 minutes, with a standard deviation of 1.8 minutes.

Assuming normal populations with equal standard deviations, and using the 0.10 level, is there a significant difference between the two routes?

Construct and interpret the 90% confidence interval for the difference between the population means.