Problem:
Mr. Lopez has a choice of two routes to get to work. Route A is 6 miles long, and his average speed along this route is 30 miles per hour. Route is 5 miles long, and his average speed along this route is 40 miles per hour, except for a -mile stretch in a school zone where his average speed is 20 miles per hour. By how many minutes is Route B quicker than Route A?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The time required for Route A is 6 miles divided by 30 miles per hour, which is hour. The time required for Route is miles divided by 40 miles per hour, plus mile divided by 20 miles per hour, which is hour. The difference in time is
hour. This is equivalent to minutes.
The problems on this page are the property of the MAA's American Mathematics Competitions