Two Plus Two Older Archives The Quizshow
 FAQ Members List Calendar Search Today's Posts Mark Forums Read

#1
08-05-2002, 08:04 AM
 Guest Posts: n/a
The Quizshow

Hi there...

Here is an old but good one. (please excuse my spelling and choice of words - english is not my first language)

You are the last person left in a quizshow. You now have the possibility to win a car. The quizmaster shows you 3 doors. Behind 1 of them, there is a car. Behind the other 2 there is nothing. He tells you to pick a door, and you do. The door remains closed. Now he says: "I'll help you - I'll show you a door with nothing behind. He opens 1 of the doors that you didn't pick. Now he says: "Would like to change your mind and pick the other closed door, or would you like the one you've picked in the first place?"

Now you have 3 options:

1) Change your mind, and pick the other door

2) Stick to the door you've picked first

3) It doesn't make any difference

Well - what's it gonna be (And why!)

Yours

Mik

#2
08-05-2002, 08:33 AM
 Guest Posts: n/a
switch

I'll let other's elaborate.
#3
08-05-2002, 12:37 PM
 Guest Posts: n/a
Re: switch

Ditto as to Bruces' response.

Jimbo

#4
08-05-2002, 03:08 PM
 Guest Posts: n/a
Re: switch

Originally, was 2/3's chance of NOT being the door you selected... so it's 66.7% that it's behind the other door
#5
08-05-2002, 07:24 PM
 Guest Posts: n/a
Re: The Quizshow

It doesn't make any difference.

They are going to show you a door with nothing behind it anyway, whether you pick the right one or not. The 33.3% chance that the door they opened will split evenly between the two doors remaining.

If in a three-handed no ante HE game all three of you are dealt AKs, preflop your chance of winning is proportional to the number of players in the hand. One of them folding doesn't suddenly give either one of you 2/3 of the equity.
#6
08-05-2002, 09:19 PM
 Guest Posts: n/a
Re: The Quizshow

Ok Monte let's play. I'll switch doors and give you even money odds. Since you think I'm an 2-1 dog you should be eager to play.
#7
08-06-2002, 03:19 PM
 Guest Posts: n/a
Re: The Quizshow

BruceZ is right. Here's how it works:

Let's say that you don't change your mind. The probability that you pick the door with the car behind is 1/3. So if you don't change your mind you will win the car 1 out of 3 times.

Now, let's say that you change your mind every time. The probability that you picked the door with the car behind is still 1/3. Let's say the car is behind door #1:

1) You pick door 1 (Quizmaster opens door 2 or 3)You switch = No car

2) You pick door 2 (Quizmaster opens door 3)You switch = Win the car

3) You pick door 3 (Quizmaster opens door 2) You switch = Win the car

The correct answer is to change your mind and switch. The strange thing is, that 4/5 people that you give this riddle to, will stick to their intuition and hang on to the door they picked first.

Has anyone got any ideas on how to use this at the pokertable? How about you BruceZ?

Yours

Mik

#8
08-06-2002, 07:34 PM
 Guest Posts: n/a
Re: The Quizshow

There are many poker applications of Bayes' therorem which is what this is based on. Sklansky gave an example recently from jacks or better draw poker where the odds that your opponent has a set go from 2% to 10% once the player opens since you now know that he has jacks or better.

In fact, much of reading hands involves modifying the probabilities of what hands your opponent has based on additional information you gain on each round by the way he bets. You in turn attempt to keep your opponent from doing the same thing to you by making him miscalculate the probabilites of certain hands that you might hold. You do this either by playing in a way that changes the probability of the hand you are holding relative to other hands, or by sometimes playing hands in a way that is different from how you normally play them so that your opponent will miscalculate on future hands.

Revealing information which causes others to calculate whatever probabilities you want them to calculate is also used between nations in economic matters.

 Thread Tools Display Modes Hybrid Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Two Plus Two     Two Plus Two Internet Magazine     About the Forums     MOD DISCUSSION     ISOP General Poker Discussion     Texas Hold'em     Beginners Questions     Books and Publications     Televised Poker     News, Views, and Gossip     Brick and Mortar     Home Poker     Poker Beats, Brags, and Variance     Poker Theory Limit Texas Hold'em     Mid- and High-Stakes Hold'em     Medium Stakes Hold'em     Small Stakes Hold'em     Micro-Limits     Mid-High Stakes Shorthanded     Small Stakes Shorthanded PL/NL Texas Hold'em     Mid-, High-Stakes Pot- and No-Limit Hold'em     Medium-Stakes Pot-, No-Limit Hold'em     Small Stakes Pot-, No-Limit Hold'em Tournament Poker     Multi-table Tournaments     One-table Tournaments Other Poker     Omaha/8     Omaha High     Stud     Other Poker Games General Gambling     Probability     Psychology     Sports Betting     Other Gambling Games     Rake Back     Computer Technical Help Internet Gambling     Internet Gambling     Internet Bonuses     Software 2+2 Communities     Other Other Topics Other Topics     Sporting Events     Politics     Science, Math, and Philosophy     The Stock Market

All times are GMT -4. The time now is 10:40 AM.