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Two persons each divide $1000 into three different amounts and compare highest with highest, middle with...

decision/divide.1000 New

New entry, edited from material collected for the archive and not yet in a released version.

Problem

Two persons each divide $1000 into three different amounts and compare
highest with highest, middle with middle and smallest with smallest;
whoever is larger in two of the three comparisons wins.  What division
is best against an opponent who divides randomly?

Two persons each divide $1000 into three DIFFERENT amounts.  Then they
compare their highest, medium and smallest amounts.  The person who has
2 of the 3 times the highest amount, gets $1000.

The question is what division is most profitable, assuming that your
opponent divides randomly?

The following division emerged from my computer simulations:
401/400/199.  But there should be a better one.

Can someone come up with a better solution?

-- Marco Meijers
Show solution
nh <noelh@hooked.net> wrote:
>I'd go with 1 + 499 + 500
>figuring I'd always lose the minimum, but win the medium and
>highest, winning the 1000.

I'll take 2 + 3 + 995 and beat you.  :-)

Actually, I analyzed all 83,333 different partitions of 1000, and found
that 231 + 384 + 385 wins over 63833 of them, while 1 + 499 + 500 wins
over only 21,082.  I'm still trying to decide if each of the 83,333
different partitions is equally likely in a random partitioning, or if
some of them are more likely than others.  I counted them all equal in
the above.

-- Dave Dodson <dodson@convex.com>

[ Editor: 83,333 = round(1000^2/12) is the number of partitions of 1000
into three positive parts with repeats allowed; with three different
parts, as the problem requires, there are round(997^2/12) = 82,834. ]