Posted by Denis Borris on September 20, 2002 at 02:01:21:
In Reply to: How many routes? posted by Marin on September 20, 2002 at 01:30:07:
: this is a problem of the week we got
: Joe walks to Pele's house each day, then Joe and Pele walk to school together. They always walk eithier east or north. Pele lives two blocks south and three blocks west of school and 1 block east and two blocks north of joe. How many routes can Joe take to school?
Draw a 3 by 2 rectangle: label top right corner S (School), bottom left P (Pele).
Draw straight lines in rectangle such that it now contains 6 squares.
Attach to corner P the corner of a 2 by 1 rectangle (heading south) and label
the bottom left corner J (Joe).
Draw a straight line inside, so you get 2 squares.
It is now easy to see that Joe can get to Pele's in 3 different ways:
east-north, north-east-north and north-east.
Now figure out the number of ways from P to S: it's your DAMN puzzle;
why should we do all your work :)