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Subj:.....The Ferry Boat Problem (S642)
          From the book 
            "More Mathematical Puzzles of Sam Loyd" 
          Edited by Martin Gardner 
          From: Dover Publications in 1960
 

What is the exact width of the Hudson River?

Two ferry boats start moving at the same instant from
opposite sides of the Hudson River, one boat going fron
New York to Jersey City and the other going from Jersey
City to New York.  One boat is faster than the other,
so they meet at a point 720 yards from the nearest shore.

After arring at their destinations, each boat remains ten
minutes in the slip to change passengers; then it starts
on its return trip.  The boats again meet at a point 400
yards from the other shore.  What is the exact width of
the river?

The problem shows how the average person, who follows the
cut-and-dried rules of mathematics, will be puzzled by a
simple problem that requires only a slight knowledge of
elementary arithmetic.  It can be explained to a child,
yet I hazard the opinion that ninety-nine out of every
hundred of our shrewdest businessmen would fail to solve
it in a week.  So much for learning mathematics by rule
instead of common sense which teaches the reason why!

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