All of this discussion and its not even Friday afternoon! :) Stacey
> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Steven Knight > Sent: Thursday, 5 August 2004 16:25 > To: 'NZ Borland Developers Group - Delphi List' > Subject: RE: [DUG] Welcome back problem > > > I like it. Option C contains 2 possibilities > C: Got the car this time, the presenter shows that there is a > goat behind door 2 (or 3) Stay - Car Swap - Goat > > or look at it this way: > The combination matrix is actually like this: (With 2 goats) > > G1 G2 C > G2 G1 C > G1 C G2 > G2 C G1 > C G1 G2 > C G2 G1 > > > Your change of being right first time is ~.333 > I follows that the presenter has a probability ~.666 of > having to eliminate the second goat. > > So swap to the ~.666 probability > > > > > > I thought I had a good explination > > > > > > Here is my table again > > > A: G G C > > > B: G C G > > > C: C G G > > > > > > A: represents Goat behind doors 1 & 2 and Car behind Door 3 > > > > > > Lets continue to assume that we still always pick door number 1 > > > > > > A: We've chosen a goat (however we don't know this). > The presenter > > > will now tell us that there is a goat behind door 2. What > > happens if we > > > stay or swap? > > > Stay - Goat > > > Swap - Car > > > > > > B: Still chosen a goat, the presenter shows us that there > is a goat > > > behind door number 3. And again here is what happens if we > > stay or swap. > > > Stay - Goat > > > Swap - Car > > > > > > C: Got the car this time, the presenter shows that there > is a goat > > > behind door 2 (or 3) Stay - Car > > > Swap - Goat > > > > > > So if we stay we get Goat, Goat, Car, thus 1 out of 3 times > > we get the > > car. > > > > > > If we swap we get Car, Car, Goat - 2 out of 3 times we > get the car. > > > > > > The same arguments apply if we initially chose door 2 or door 3. > > > > > > I hope this explination makes things clearer. I think the main > > > confusion is from trying to assign probabilities. If I've missed > > > something and am wrong then will somebody explain my confusion in > > > language simple enough so that I can understand it ;-) > > > > > > However I think that the test applications also show that > > the answer is > > > correct even if my reasoning is wrong. > > > > > > Alister > > > > > > > > > Paul M - ProSouth wrote: > > > > Ok, if he opens door 2 to reveal the goat, we now know > > that option B > > (GCG) > > > > is incorrect, leaving: > > > > > > > > A: G G C > > > > C: C G G > > > > > > > > Again, a 50/50 scenario. > > > > > > > > Regards, > > > > > > > > Paul Matthews > > > > ProSouth Technology Solutions > > > > Phone: +64 3 470 1321 > > > > DDI: +64 3 470 1324 > > > > 0800 PROSOUTH (0800 776 768) > > > > 249 Cumberland Street, Dunedin, New Zealand > > > > Visit us at www.prosouth.co.nz > > > > > > > > ----- Original Message ----- > > > > From: "Stacey Verner" <[EMAIL PROTECTED]> > > > > To: "NZ Borland Developers Group - Delphi List" > > <[EMAIL PROTECTED]> > > > > Sent: Thursday, August 05, 2004 2:11 PM > > > > Subject: RE: [DUG] Welcome back problem > > > > > > > > > > > > > > > >>We aren't assuming that he opens door 3. He will open a > > door with a > > > >>goat, which in case A is door 2. > > > >> > > > >>Stacey > > > >> > > > >> > > > >>>-----Original Message----- > > > >>>From: [EMAIL PROTECTED] > > > >>>[mailto:[EMAIL PROTECTED] On Behalf Of Paul > > M - ProSouth > > > >>>Sent: Thursday, 5 August 2004 14:03 > > > >>>To: NZ Borland Developers Group - Delphi List > > > >>>Subject: Re: [DUG] Welcome back problem > > > >>> > > > >>> > > > >>>What you are ignoring is the additional information. > > > >>> > > > >>>Using your matrix, the host opens door 3 to reveal a > goat. This > > > >>>now removes Option A, G G C, as being a > > possibility, leaving: > > > >>> > > > >>>B: G C G > > > >>>C: C G G > > > >>> > > > >>>There is now a 50% chance that the car is behind door 1 or 2. > > > >>> > > > >>>Regards, > > > >>> > > > >>>Paul Matthews > > > >>>ProSouth Technology Solutions > > > >>>Phone: +64 3 470 1321 > > > >>>DDI: +64 3 470 1324 > > > >>>0800 PROSOUTH (0800 776 768) > > > >>>249 Cumberland Street, Dunedin, New Zealand > > > >>>Visit us at www.prosouth.co.nz > > > >>> > > > >>>----- Original Message ----- > > > >>>From: "Alister Christie" <[EMAIL PROTECTED]> > > > >>>To: "NZ Borland Developers Group - Delphi List" > > <[EMAIL PROTECTED]> > > > >>>Sent: Thursday, August 05, 2004 1:36 PM > > > >>>Subject: Re: [DUG] Welcome back problem > > > >>> > > > >>> > > > >>> > > > >>>>There are 3 possible arrangements > > > >>>> > > > >>>>A: G G C > > > >>>>B: G C G > > > >>>>C: C G G > > > >>>> > > > >>>>if we assume that we choose door number 1 each time > > > >>>> > > > >>>>in both A & B we have choosen incorrectly and switching > > > >>> > > > >>>will give us > > > >>> > > > >>>>the correct answer (presuming the presenter always > > reveals a goat) > > > >>>> > > > >>>>In C we have choosen correctly and if we switch we loose. > > > >>>> > > > >>>>So 2 out of 3 times if we switch we win, so I think > > > >>> > > > >>>switching is our > > > >>> > > > >>>>best bet. > > > >>>> > > > >>>>Alister > > > >>>>_______________________________________________ > > > >>>>Delphi mailing list > > > >>>>[EMAIL PROTECTED] > http://ns3.123.co.nz/mailman/listinfo/delphi > > >>>> > > >>>> > > >>> > > >>>_______________________________________________ > > >>>Delphi mailing list > > >>>[EMAIL PROTECTED] http://ns3.123.co.nz/mailman/listinfo/delphi > > >>> > > >> > > >>_______________________________________________ > > >>Delphi mailing list > > >>[EMAIL PROTECTED] > > >>http://ns3.123.co.nz/mailman/listinfo/delphi > > >> > > >> > > > > > > > > > _______________________________________________ > > > Delphi mailing list > > > [EMAIL PROTECTED] > > > http://ns3.123.co.nz/mailman/listinfo/delphi > > > > > > > > _______________________________________________ > > Delphi mailing list > > [EMAIL PROTECTED] > > http://ns3.123.co.nz/mailman/listinfo/delphi > > > > _______________________________________________ > Delphi mailing list > [EMAIL PROTECTED] > http://ns3.123.co.nz/mailman/listinfo/delphi > > > Visit us online at http://www.ecan.govt.nz > > > > ********************************************************************** > This email and any files transmitted with it are confidential and > intended solely for the use of the individual or entity to whom they > are addressed. 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