2.60 U.S. Interstate 64 runs between Portsmouth, VA, at I-264 on the eastern end to St. Louis, MO, at I-270 on the western end. While passing through six states and five more major cities, I-64 intersects nine more interstate highways. The number of miles in each state is as follows:

Missouri—16 miles, Illinois—132 miles, Indiana—

124 miles, Kentucky—191 miles, West Virginia—

183 miles, Virginia—299 miles. (A diagram may be helpful.)

Source: http://www.ihoz.com/I90.html

a. Find the mean distance between major cities along I-64.

b. Find the mean distance between interchanges with interstate highways along I-64.