Assuming that the Earth is spherical and recalling that latitudes range from 0° at the Equator to 90° N at the North Pole, how far apart, measured on the Earth's surface, are Dubuque, Iowa (42.50° N latitude), and Guatemala City (14.62° N latitude)? The two cities lie on approximately the same longitude. Do not neglect the curvature of the Earth in determining this distance.