Thursday, July 21, 2011

Bronx vs. Brooklyn

A young man lives in Manhattan near a subway express station. He has two girl friends, one in Brooklyn and one in the Bronx. To visit the girl in Brooklyn, he takes a train on the downtown side of the platform. To visit the girl in the Bronx, he takes a train on the uptown side of the same platform. Since he likes both girls equally well, he simply takes the first train that comes along. In this way he lets chance determine whether he rides to the Bronx or to Brooklyn. The young man reaches the subway platform at a random moment each Saturday afternoon. Brooklyn and Bronx trains arrive at the station equally often - every 10 minutes. Yet for some obscure reason, he finds himself spending most of his time with the girl in Brooklyn: in fact, on the average he goes there nine times out of ten. Can you think of a good reason why the odds so heavily favor Brooklyn?

:) Yeee, it's not a morally right scenario, but the reason is a good one.. I like the riddle..

3 comments:

  1. Would they depart every 10 minutes and their departing intervalls be shiftet by 5 minutes, there would be an equal chance to get one of both trains. In this case it seems like the train's departing intervall is shiftet by 1 minute, so the time frame for the chance to catch Train 2 is only 1 minute wide. Thus the chance to hop on Train 1 is 9/10 and for Train 2 it is 1/10 (intervall unit being [min]). Correct? :)

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  2. That's it, yeah :)
    Of course, I suppose it wouldn't work in reality in NYC (u know.. "in theory there is no difference between theory and practice, but in practice, there is."). However, your reasoning is absolutely correct.

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