Lets see how smart you guys are...

[Dan Juday]

I miss Monty Hall.

 

So, in this question, what costume am I wearing? I always wanted to be the big bear.

[datsunlover]

I guess it depends on where you live.. some parts of the world a donkey would be the better prize...

[Guest Phailure]

You should stay with door 2 because if door 2 didnt have the car, then the host or whatever would have opened the door and shown you that you didnt get the car.

[80LS1T]

Ok I for one am dying to know the answer to this question!

 

I say stick with the first door you pick because whenever humans are involved with a choice, anything can happen.

 

 

Guy

[Guest ericmendenhall]

(I'm an engineer, by the way)

 

You should switch; your odds improve.

I know it's counterintuitive but it's true.

 

Marilyn Vos Savant asked this once and I worked out all the permutations to settle an argument with my coworkers.

 

In the beginning you had a 1/3 chance of picking the prize.

If you do not switch, this does not change.

 

If you switch every time, then you have a 2/3 chance of being right,

and only a 1/3 chance of being wrong. Why?

 

Just try looking at all the possibilities, prize = A, no prize = B,C

A,B,C: you pick A, are shown B, swap to C to lose the prize.

A,B,C you pick B, are shown C, swap to A to win the prize

A,B,C: you pick C, are shown B, swap to A to win the prize

 

So 2/3 chance you win, 1/3 chance you lose if you swap.

Even if you include all permutations the odds stay the same.

 

Another way of looking at it is that opening the door adds information to the system, which goes unused if no action takes place.

Yeah I know it doesn't seem to make sense at first.

[Pop N Wood]

There is one more possiblity. Pick A, shown C and swap to B losing the prize.

 

Wouldn't that make it 2 for 2?

[Dan Juday]

O.k. nobody would bite on my bear costume wise crack so I'll give it a go.

 

First time you pick you have a better chance of losing than winning. So odds are you picked wrong. Next pick odds improve from 1/3 to 1/2. So since you probably picked wrong the first time, and your odds are better the second time, you should change your guess.

 

Is that about it?

 

I aced trig and calc and loved that stuff (and have sumarily forgotten it all) but I never took statistical probability. Probably would have helped with some of the choices I've made over the years.

[DemonZ]

Is it assumed the host does not want you to win and knows what are behind all doors? In other words, he will always:

 

1) open the non winner first (the empty one)

 

2) offer you a choice to switch your original choice

 

 

OT,

 

RE: manhole cover, besides not falling in, added benefits are: a round cover will seat in infinite positions, and you can roll it to move it.

[utvolman99]

(I'm an engineer' date=' by the way)

 

You should switch; your odds improve.

I know it's counterintuitive but it's true.

 

Marilyn Vos Savant asked this once and I worked out all the permutations to settle an argument with my coworkers.

 

In the beginning you had a 1/3 chance of picking the prize.

If you do not switch, this does not change.

 

If you switch every time, then you have a 2/3 chance of being right,

and only a 1/3 chance of being wrong. Why?

 

Just try looking at all the possibilities, prize = A, no prize = B,C

A,B,C: you pick A, are shown B, swap to C to lose the prize.

A,B,C you pick B, are shown C, swap to A to win the prize

A,B,C: you pick C, are shown B, swap to A to win the prize

 

So 2/3 chance you win, 1/3 chance you lose if you swap.

Even if you include all permutations the odds stay the same.

 

Another way of looking at it is that opening the door adds information to the system, which goes unused if no action takes place.

Yeah I know it doesn't seem to make sense at first.[/quote']

 

This is the correct answer! I am actually pretty impressed that anyone came up with the right answer. I help in the training of Six Sigma Green Belts for my company. I currently work as a Black Belt. We always ask this question and no one has got it yet. Even when the answer is given most dont understand.

 

Any easy way to look at it is that you will pick the correct door only 1/3 of the time. Once the other door is opened you only have two possible doors to pick. You have a 1/3 chance that the door you already have picked is the right door and therefore a 2/3 chance that the other door is the right door.

 

So you ALWAYS switch!

[jasonfen]

Everything is fifty fifty. You either guessed right or you guessed wrong. At least that is my viewpoint.

[Pop N Wood]

Like I said, this is an old problem. Don't really like the explanation above because it gets too confusing what a valid permutation is.

 

The easy way to look at this is there are only two possible courses of action: either you switch or you don't switch. If you don't switch, the odds of getting it right are 1 in 3. Can’t change that. That means the remaining 2 out of 3 chance has to fall with the other option: switching doors.

 

Another way of looking at this is you are being allowed to pick 2 doors and get to throw one of them out after you know what is behind them.

 

Of course old Monte will trick you up.

 

BTW, WTF is a "Six Sigma Black Belt"? What does this have to do with Kung Foo anyway? Is this just a Tennessee thing?

[Tim240z]

Six Sigma is the top section of distribution of the statistical bell shaped curve...generally referring to product reliability. I believe that Motorolla was the first Six Sigma Company.....

[utvolman99]

Six Sigma is the top section of distribution of the statistical bell shaped curve...generally referring to product reliability. I believe that Motorolla was the first Six Sigma Company.....

 

That is Six Sigma. But Six Sigma as a program is a project methodology. There are four designation for Six Sigma positions at most companies.

 

White Belt - Educated in very general six sigma methodology

Green Belt - A little more education and must complete a project using six sigma methodology

Black Belt - Full time position uses statistical analysis tools and structured approach to solve major issues affecting quality

Master Black Belt - Is more or less the black belts boss

 

At DuPont they require all engineers to be Green Belt certified. Also, if you want to be promoted into management you must be Black Belt certified.

[Guest Phailure]

All im going to say... is you dont win at poker by playing the odds... but i guess that explanation makes enough sense

[grumpyvette]

having worked in manholes for AT&T ENGINEERING I can tell you WHY they use round covers

(1) as stated above they wont fall into the hole if dropped in place incorrectly

(2) when they are cast they cool more evenly and dont tend to warp or need as much machine work

(3) only a ROUND cover can be stood on edge and rolled out of the way for work clearance,(some covers weight 300lbs-700lbs)

(4) manhole lids(covers) are tapered on the under edge so they self center and lay flat when weight like trucks are passing over them, a square cover might tend to jump up on the far edge as weight is applied suddenly to the near edge, round covers wont do that

(5)(manhole covers have an inner lower lip for the hook that removes them to grasp) since they can be dropped into any position only a round cover gives equal stress when lifted by one edge, and thats inportant if they were to be dropped in place upside down, and need to be flopped over

(6) manholes are round because the round shape allows the maximum area for the minimum circumferance allowing the lowest material weight and voluum to strength and opening area for workers and material to pass thru, when your casting a 100,000 at a time the extra metal voluum in square lids adds up fast, not to mention the extra machine work and weight for shipping them

[Kevin Shasteen]

.., Master Black Belt - Is more or less the black belts boss..,

 

...., and that would be the boss's wife!

 

Kevin,

(Yea,Still an Inliner)

[Guest ericmendenhall]

Ahhh... basking in the glow of my brainwaves...

 

 

 

Hey, are we supposed to call them PERSON-hole covers now?

I can never keep up with the latest PC jargon.

[Poundz9oh9]

is there anything you DON'T don't do Grumpy......????

[RPMS]

Sorry, I'm calling bullsh;t. No matter how smart Ms VosSavant is, it doesn't change the fact that there is a donkey behind one door, and a car behind another. You have a 50/50 chance, regardless of whether you switch or not.

 

The thing to remember about statistics is that NOTHING THAT HAPPENED IN THE PAST HAS ANY BEARING ON WHAT YOUR ODDS ARE. You and Ms. Savant are neglecting this in your calculations. Even if you flip a quarter ten times and get ten heads, the odds of getting a head on the next flip will be 50/50.

 

Sorry to burst your bubble. You're overthinking it.

[wheelman]

RPMS,

I agree with you but the statistics calculations being used don't account for the fact that the car is only behind 1 door. The idea is that your odds are better if you change your selection because you would have chosen the 1 door with the car at some point in the process, not that you ended up on the correct door.

 

This discussion reminds me of a book I've read several times called "In Search of Schrodinder's Cat". The book is a laymans description of the theories of Quantum Physics. It tries to explain the fact that its not possible to simultaneously measure the velocity and position of a sub-atomic particle and the implications this has on the reality of how the universe works. This is called the Paully (sp) Exclusion Principle and it states that to measure either the position or velocity of the particle makes the other property non-measurable.

 

This experiment with the three doors is similar in that the reality of which door the car is behind is not established until after the choices have been made and if you change your selection you will have effectively selected the correct door at some point even though it may not have been your final selection. Not exactly the same as Schrodinger's Cat which is alive and dead at the same time in the experiment in the book but similar in that as far as you know the car is behind both doors at the same time and the reality of where it really is is only established by interacting with the experiment. If no interaction is made with the experiment nothing can be said about where the car is, so it's behind all the doors and so is the donkey.

 

I know this probably doesn't make sense unless you've studied quantum physics and even then it doesn't make sense. Assuming I described it in enough detail this should bother you.

 

Wheelman