Thursday, August 10, 2006

Guest post -- Puzzle by Arvind




The Buddha at the Kalachakra temple in McLeod Gunj.
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Arvind had posted this as a comment a while back:


To enliven the proceedings, here's a nice little puzzle (I define nice puzzles as simple questions with answers that are obvious only with the right way of looking at them.)

A group of 400 students stand 20 students in each row and 20 students in each column.





Person A goes ROW wise and mentally makes a note of the shortest person in each row. Then he picks the tallest of these people. Denote this persons height P_1.

Person B goes Column wise and mentally makes a note of the tallest person in each column. Then he picks the shortest of these people. Denote this persons height P_2.

What claims can be made about P_1 and P_2
( a ) P_1 >= P_2
( b ) P_1 <= P_2
( c ) P_1 = P_2
( d ) No relationship exists.

Arvind


==
This may be the last post from my IBM T41 laptop from Juniper. Goodbye electronic friend, you have been with me through lots of ups and downs, good things and indiscretions. We've been to the US, Europe and Visakhapatnam :-).


4 comments:

Anonymous said...

Arvind's puzzle sure brings back nightmares of the analytical section of GRE :-)
Sajini

Anonymous said...

SOLUTION TO PUZZLE:

DONT READ ANY FURTHER IF YOUR DONT WANT THE ENJOYMENT OF SOLVING IT.





solution:
Shortest of tallest in Columns >= tallest of shortest in Rows.

In the event that the person selected by A and B happens to be the same, then obviously, shortest of tallest equals tallest of shortest.

In the event that the persons selected by A and B are different, then consider the person at the intersection of the row of P_1 (tallest of shortest) and the column of P_2 (shortest of tallest.) Call this person x. P_1 <= x because P_1 is the shortest in the row and x is on the same row. Similarly x <= P_2 because x and P_2 are on same colume and P_2 is the tallest on that column. Thus we conclude that
P_1 <= x <= P_2 or that the shortest of tallest in columns >= tallest of shortest in rows.


Arvind

Anonymous said...

you mean mostest fattest and leastest fattest ....

Humpty Dumpty sat on a wall.
Humpty Dumpty had a great fall.
All the king's horses and all the king's men
Couldn't put Humpty together again.

nice day everybody!!!!!!!

hi hello said...

its great man