[dba-Tech] The Three Doors Problem

I think you misunderstood the NHL ping pong entry draft; I didn't explain it 
too clearly in my first attempt.  the one thing I forgot to mention is that 
once a team is selected, all of the remaining ping pong balls of the team 
are removed from the pool. this way, every team is represented only once in 
the top 30 entry draft positions.

therefore, in the reverse selection scenario, if we are down to the last two 
teams, if one team has three ping pong balls and the other has one ping pong 
ball, the team with only one ping pong ball is the favorite because that 
team has less chance of being selected for the second pick.

Billy


>From: "Stuart McLachlan" <stuart at lexacorp.com.pg>
>Reply-To: Discussion of Hardware and Software 
>issues<dba-tech at databaseadvisors.com>
>To: Discussion of Hardware and Software issues 
><dba-tech at databaseadvisors.com>
>Subject: RE: [dba-Tech] The Three Doors Problem
>Date: Sat, 27 Aug 2005 10:18:34 +1000
>
>On 26 Aug 2005 at 19:20, Billy Pang wrote:
>
> > first ping pong ball selected gets first pick in the entry draft, the 
>teams
> > with three ping pong balls have a greater chance of getting the coveted
> > first pick than the other teams with only two or one ping pong ball.  I
> > watched the draft live as it took place.  To increase drama, they select 
>the
> > ping pong balls behind closed doors to determine the order of the thiry
> > teams; then they come out and reveal the order in reverse (starting with 
>30,
> > 29, 28, etc...); however, i realized that if they pick the ping pong 
>balls
> > in reverse order (ie. first ball they picked is 30th pick), the teams 
>with
> > three ping pong balls would no longer be favorites because they have a
> > greater chance of being selected.
>
>  They are still favourites.  A team with three balls still has two balls 
>in
>the running for 1st even if one of their balls comes up as 30th. They are
>still better off than a team with only one ball.
>
>Take it to it's logical conclusion.  Imagine you get down to the "last"
>three picks  (3rd,2nd,1st)  and have two teams left - one with two balls
>and one with one ball.  How often will the team with one ball end up with
>the 1st draft and how ofter will the team with two balls get him?
>
>--
>Stuart
>
>
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