Riddle

You are the train driver.
You have four trains to drive from New York to Boston.

You can transport two trains at one time by linking them.

After you drive to Boston, TO RETURN TO THE REMAINING trains that are back in New York, you need to drive A train back from Boston to New York. This is necessary, to return to New York so you can then transport to Boston the other trains that you left behind.

Each train has a different speed at which it can travel.
one train  takes 5 hours to travel the distance
another   takes 4 hours to travel the distance
another   takes 2 hours to travel the distance
and another takes 1 hour to travel the distance.

When two trains are linked together, it takes the amount of time of the slower trains' speed.

For example, if you link the '5 hour' train with the '1 hour' train, it will take 5 hours. Then, to get back to New York, you can take the '1 hour' train. Which now leaves a total of 6 hours of driving so far. And if then you link the 1 hour train with the 2 hour train, and take those to Boston, you add two more hours to your travelling, for a total, so far, of 8 hours.

For the riddle, Whats the shortest amount of time in which you can drive all the trains to Boston? And how do you do it?

matty

its possible in less time

psymonstark

yes thats it!

Pnevermind

Cheating:

haha nice try cbt!

Wait so I can't start the 5 hour train with 4 in tow, then jump off. Run back and hook the 1 hour train to the 2, and start it 2 hours and 59 minutes later, so it catches up to the 5 hour train just as it arrives, so I can Hit the brakes on the 2 hour train, jump onto the back of the 4 hour train, run up to the 5 hour train and hit the brakes on it? Awww man.

Only superman is faster than a train....oh and the flash

New Riddle -

You are to deliver a package to your robot-contact, John. The package contains super classified information and cant fall into enemy hands. The enemy has sent a double to intercept the package; they sent robot- Tom. They both meet you at the rendezvous, and you cant discern any physical differences between them. they both claim to be John.

The only tool available (in the riddle) is to ask only one robot one question. But one of the robots always tells the truth, and one of them always lies. You don't know which of them is the liar, and which is the truthful one.(it wasn't in the dossier...)
You are further limited in that your question is limited to three words.

What can you ask either of the robots to conclusively determine which one is John?

Matty, those are three very long (and spaced) words

@Psymon, oh, missed the three word part My english is not good enough to think of an answer in three words though.