Fri Apr 02, 2010 9:36 pm
Am I missing something here? We can ascertain that the train is traveling four times the speed of the genius, but aren't we just assuming the genius is going at his maximum speed, which was stated at 10 mph?
If he is moving at 6 mph, and can beat/meet the train at either end "just in time" then the train would be moving at 24 mph.
The only facts we can conclude are that the genius can cover 3/8 of the bridge, whichever direction, in the time it takes the train to reach the bridge. So if he is heading the same direction as the train, he will cover the remaining 2/8 (or 1/4) of the bridge in the amount of time the train will cover the entire bridge, which is 8/8 or 4/4.
The train covers 4/4 of the bridge in the time the genius covers 1/4 of the bridge, so the train is traveling four times the speed, whatever the speed the genius is traveling. Therefore my answer to the question is, the train is traveling four times as fast as the genius, but no faster than 40 mph since the genius' top speed (stated) is 10 mph.
Would I be traveling at MY top speed? You'd better believe it! But it wasn't stated in the problem that the genius was moving at his top speed, only that he CAN run 10 mph, not that he was.
Okay, am I missing something?
By the way, May walked five blocks down the street with her umbrella in her hand, but never opened it, while everyone around her had theirs open and up, and yet she didn't even get wet! Explain this (easy). I'm guessing most of you know this, I'm just trying to demonstrate the same principle with Neil's problem.
Jerry