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A Boy, a Girl, and a Dog (Posted on 2004-01-24) Difficulty: 3 of 5
A boy, a girl and a dog are standing together on a long, straight road. Simultaneously, they all start walking in the same direction: The boy at 4 mph, the girl at 3 mph, and the dog trots back and forth between them at 10 mph. Assume all reversals of direction instantaneous.

In one hour, where is the dog and in which direction is he facing?

See The Solution Submitted by DJ    
Rating: 4.0000 (8 votes)

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the solution is posted, but... | Comment 14 of 15 |
okay, so I realize this isn't right, however, after reading peoples comments I think I have found a possible answer... Because it makes no sense for the dog to be going back and forth between the two people because he will never be between them unless he either starts later or turns around, why don't we just start at the end? At the end, the boy will have traveled 4 miles, and the girl 3 miles... That leaves them one mile apart. Now the dog is traveling at 10mph, which means that after 1 hour he will have traveled 10 miles... so he must have traveled 4 miles to the boy, then 1 back to the girl and so on until he ends up next to the boy at the end... Once again, I know this isn't right conceptually or otherwise, but who cares? It gets rid of pondering where he started because really, whether he starts with the girl or the boy he has to end up trotting 10 miles in 1 hr.... soo... the monkeys at the gypsie
  Posted by sean on 2005-08-23 02:08:12
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