Another way to look at it is to use a deck of cards instead. I lay them face down and ask you to pick one without turning it over. What are the chances
it's the Ace of Spades? What are the chances it's not? Now I turn over 50 of the remaining cards, none of which are the Ace of Spades. Should you
switch to the last remaining card? If you think it's a 50/50 shot, do you then think that doing this experiment 100 times would yield you picking the Ace
of Spades out of a deck 50 times?
0 Kudo
- Survivor Sucks
- Lions, Tigers, Survivors - Oh My!
- Survivor Spoilers
- MESS Hall Tribal Council
- MESS Hall Archive
- Survivor Speculation
- Survivor 20+
- The Amazing Race
- Big Brother
- Big Brother - PAST SEASONS
- The Apprentice
- American Idol
- American Idol PAST SEASONS
- The Mole
- Lost
- Other Shows That Suck
- Off Topic
- Clubs That Suck. No, Really.
- The Dump
- Monster Island
- Purgatory
- FAQ
- In Memory, 9/11/01
Monty Hall's riddle
| Started By | Comment | ||
|---|---|---|---|
 Antithesys |
|||
|
Posts: 22644 (08/10/08 9:51 AM) Gadabout |
|
||
|
UrbanRenewal |
|||
|
Posts: 102 (08/10/08 9:53 AM) |
Imagine if someone says, pick a number between 1 and a 1,000,000. If you pick the right one, you win a million dollars. So you pick number 412,000.
The host then says he's eliminating 999,998 numbers, leaving you with 412,000 and 866,437. Do you stay with 412,000? You really shouldn't. |
||
|
glazerboy |
|||
|
Posts: 2674 (08/10/08 10:23 AM) Registered User |
When there are 3 doors available your chances of picking the correct one are 1 in 3. However, once you pick a door, your chances drop to 50/50 because, as Anti
said, you know that one of the remaining doors is empty. So the situation is between Set A, which is your door, or Set B, which you know contains at least one
empty door and possibly a winning door. You now have a 50% chance of being in the right set. Showing you the empty door is a nice piece of theater but you
already knew that one of the 2 doors was empty so it doesn't give you any new information.
|
||
|
glazerboy |
|||
|
Posts: 2675 (08/10/08 10:27 AM) Registered User |
Antithesys wrote: If in every one of the 100 trials you turn over 50 cards and none of them is the Ace of Spades, then, yes, statistically the hidden card would be the Ace
50% of the time.
|
||
|
IFY0USEEKATE |
|||
|
Posts: 896 (08/10/08 10:45 AM) Lost soul |
I was told there would be no math.
|
||
|
Jennabridges18 |
|||
|
Posts: 128 (08/10/08 10:49 AM) |
..yea this is too confusing, but i was never good with probability or riddles |
||
|
Antithesys |
|||
|
Posts: 22646 (08/10/08 11:01 AM) Gadabout |
Uh, glazer, get a friend and do the card one a few times. What you're essentially saying is that you have a 50/50 chance of picking the Ace of Spades the
first time you pick a card. The chances you picked the card, or the door, or the number in UC's case, never change.
Try and guess my birthday. You pick March 13. What are the odds you got it right? Now I'll tell you 364 days which are wrong. January 1, January 2...etc. Except July 7. Do you want to say it's July 7, or stick with your original guess? |
||
 merkyl |
|||
|
Posts: 56758 (08/10/08 11:06 AM) Registered loser |
Doesn't matter, still a 50/50 chance
|
||
|
BJ |
|||
|
Posts: 5835 (08/10/08 11:11 AM) MESS member |
It does matter. The knowledge of the host is eliminating most of the wrong choices.
|
||
|
blockhose |
|||
|
Posts: 2263 (08/10/08 11:14 AM) Treadmill martyr |
As much as it pains me to admit, Urban actually has the better explanation on how to intuitively understand what's going on (since the logic doesn't
seem intuitive with only three doors to choose from). The idea of expanding your options (picking one number out of million, then having 999,998 choices
eliminated) make it very clear that the other remaining option is correct. The same logic applies for smaller number of choices (three doors), though the odds
of the other remaining door being the correct choice isn't as big as in the 1 in a million example, it is still greater than your original choice.
This is sort of like the odds of your second child being a boy when you're first child is a boy (which is less than 50%, btw). |
||
|
Jennabridges18 |
|||
|
Posts: 139 (08/10/08 11:19 AM) |
So can you all go on like Deal or no deal and use whatever math powers you have to win? or quit when you have the highest offer?
|
||
|
Antithesys |
|||
|
Posts: 22647 (08/10/08 11:23 AM) Gadabout |
Deal or No Deal, by the way, is not the Monty Hall problem, for the simple reason that the contestant is revealing suitcases, not the host. If the player
whittles it down to a penny and a million, the chances they picked the million are indeed 50/50, even though the chances started at 1/30 (or however many cases
there are).
|
||
|
Jennabridges18 |
|||
|
Posts: 143 (08/10/08 11:29 AM) |
Ohh... so in this riddle the host knows whats behind all 3 doors and knowingly opens one that has nothing behind it from the group of 2? because if thats how
it works, then it makes more sense to me. like he doesnt randomly open one from the group of 2, so theres no chance that hed open the one that had stuff behind
it.
|
||
|
X Bilkis |
|||
|
Posts: 298 (08/10/08 11:34 AM) |
yeah the key thing that anti missed is that the host always reveals a door that has nothing behind it first
and i swear there's been a thread on this before here and i thought it was started by anti |
||
|
Hamdingers |
|||
|
Posts: 11579 (08/10/08 11:37 AM) |
I don't know about a thread, but I put it in some Question or Puzzle thread, and like...6 people in a row knew the answer. So it sorta just died.
|
||
|
Eurytol |
|||
|
Posts: 2548 (08/10/08 12:38 PM) Badass motherfucker-er
|
There's a 50/50 chance if you post in this thread you're a ginormous DORK.
|
||
|
colleenlover |
|||
|
Posts: 8359 (08/10/08 1:04 PM) Registered User |
It's been driven into my brain by the New York power analysts I work for who make gazillions -you always switch when the third door is taken away.
A choice was made in taking one of the doors away, and the percentage goes up by like 33.3 percent if you did the activity 100 times of getting the prize if you switch. |
||
|
yukugajoob |
|||
|
Posts: 814 (08/10/08 1:11 PM) |
Does any of the logic behind these choices change if the doors are on a treadmill?
|
||
|
nomii |
|||
|
Posts: 4768 (08/10/08 1:23 PM) Registered user |
welcome to 1978?
|
||
|
Roadfinder |
|||
|
Posts: 4344 (08/10/08 2:49 PM) Registered user |
As explained by Antithesys, bassoon291, and UrbanRenewal, you should switch!
Say you picked door 1 and another door is opened with nada behind it. GAME 1: PRIZE NADA NADA ~ Switch and you lose. Read this and see how even mathematicians got this wrong: http://www.marilynvossavant.com/articles/gameshow.html Marilyn vos Savant has the highest IQ ever recorded. 
http://en.wikipedia.org/wiki/Marilyn_vos_Savant |
||
- Survivor Sucks
- Lions, Tigers, Survivors - Oh My!
- Survivor Spoilers
- MESS Hall Tribal Council
- MESS Hall Archive
- Survivor Speculation
- Survivor 20+
- The Amazing Race
- Big Brother
- Big Brother - PAST SEASONS
- The Apprentice
- American Idol
- American Idol PAST SEASONS
- The Mole
- Lost
- Other Shows That Suck
- Off Topic
- Clubs That Suck. No, Really.
- The Dump
- Monster Island
- Purgatory
- FAQ
- In Memory, 9/11/01
