September 2012
Problem of the Month

From Fort Collins to Rock Springs

Mr P is taking a trip from Fort Collins, Colorado to Rock Springs, Wyoming.   He wants to arrive in Rock Springs exactly at 11:00 AM.   If Mr. P travels at 60 mph, he would arrive an hour early (at ten); if if he travels at 40 mph, he would arrive an hour late (at noon).

How far is Rock Springs from Fort Collins (using the information in this problem -- NOT Mapquest!), and how fast must he travel to arrive at 11:00 AM?

No second chances on this problem!

Solution to the Problem:

The distance from Fort Collins to Rock Springs (using the data in this problem) is 240 miles, and Mr. P would have to travel at 48 mph in order to get there at 11:00 AM.

Let x = number of hours to travel in order to get to get to Rock Springs at 11:00 AM.
Then x - 1 = hours needed if going at 60 mph
And x + 1 = hours needed if going at 40 mph.
So, the distances at these two speeds would be equal, so
60 (x - 1) = 40 (x + 1)
Solving, we get x = 5 hours.
Substituting back, we get the distance to be 240 miles.
Dividing 240 (the distance) by 5 (the hours), you get the speed: 48 mph.

Correctly solved by:

1. James Alarie	Flint, Michigan
2. Mike Bova	Wallingford, Connecticut
3. Chad Fore	Gate City, Virginia
4. Alex Jeon	----------

Send any comments or questions to: David Pleacher