All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Just Math
Simple trains problem (Posted on 2017-08-29) Difficulty: 2 of 5
A freight train going in one direction takes 3 minutes to pass a crossing. A slower train of the same length on a parallel track in the other direction takes 4 minutes.

How long does it take these trains to pass each other?

No Solution Yet Submitted by Jer    
Rating: 3.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Simple Solution (spoiler) | Comment 1 of 2
If they start head to head (on parallel tracks) then they will be alongside each other (head to foot, engine to caboose) when the faster train has traveled 4/7 of its length and the slower train has traveled 3/7 of its length.  This takes 3 minutes * 4/7 = 4 minutes * 3/7 = 12/7 minutes.  Double this to get the time at which they will have passed each other (caboose to caboose).

Final answer = 24/7 = 3 3/7 minutes.

  Posted by Steve Herman on 2017-08-29 09:57:56
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (7)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2017 by Animus Pactum Consulting. All rights reserved. Privacy Information