Can you can guess the month another person bought their Golf?

[Dubya]

one pick. two choices. 11/12. two to choose from, one chance. 11/12.

so. may or august. pick one. i would have thought that the chances of it being may, are 1/2. and the chance that it's august, is the other 1/2.

wrong. the chance that its may, is 11/12. AND, the chance that it's august, is 11/12. apparently.

and with that indisputable logic, i'm out of this debate. unless there's sheilas involved.

You've misrepresented what was written in the original post.

The sum of the probabilities for each possible outcome must equal 1. I am sure you know this and I do not know where you get two possible outcomes with a sum of 22/12 (ie >1).

As stated previously, and in the OP, the probabilities for each of the two months being correct are as follows:

May (month you chose out of 12 options): 1/12

August (only other month not eliminated by host/owner): 11/12.

Total of probabilities is 1.

Chance of winning when you chose May = 1/12.

Chance of winning after owner eliminated 10 other months = 1/12.

After all, you already knew there was an 11/12 chance 10 of the other months you did not choose were incorrect (and a 1/12 chance 11 of the other months were incorrect (ie that your choice was right and all 11 other options were wrong).

So how can the odds of being correct on the first guess go from 1/12 to 6/12 just because the owner of the car tells you the names of ten of the months that weren't correct. The names of the months is of no moment. They do not change the probability that a random choice from 12 months has a 1/12 of being the correct month.

So this extra information does not make your guess any more likely to be correct, does it?

Of course not.

So of the two months left to choose from:

Your month (May) is left because you chose it (and it has to remain, with its 1/12 chance of being correct); and

The other month, which has an 11/12 chance of being correct and a 1/12 chance of being wrong (the same odds as your month has of being right).

Whilst this is based on the Monty Hall Dilemma, and the principle is the same, 12 months were chosen in place of 3 doors simply because the larger number of options should make it obvious that your chances of picking the winner are based on the number of options that existed at the time you made your random choice, not how many options are left at the end.

So two options and two different probabilities, definitely not 1/2.

Capiche?

[Dubya]

so. may or august. pick one. i would have thought that the chances of it being may, are 1/2. and the chance that it's august, is the other 1/2.

Just taking that point about chances of it being May being 1/2.

Why is it so likely to be May when there are 12 months in the year.

Isn't each month equally likely?

If the chances of it being May are 1/2 then the chances of the 11 other months must be 1/2 as well. Which makes 600% in total so that cannot be right.

The only reason May is still an option is because the punter chose it. And the probability it is the month in question is 1/12.

Therefore, because the total of all probabilities must equal 1, the probability that August is the correct month must be 11/12.

After all, August was selected by the person who knows the answer whereas the punter chose May.

Does the punter really have the same chance of nominating the correct month as the owner of the car? Unlikely.

The owner of the car is 11 times more likely to nominate the correct month.

The only time the owner will nominate the incorrect month is when the punter nominates the correct month. Which means unless the punter lucked-out and nominated the correct month in the first place (probability 1/12) in 11/12 cases the owner will have to nominate the correct month.

So, again, there is a 1/12 chance the punter has chosen correctly the first time and a 11/12 chance they have not.

This means there is an 11/12 chance the car was delivered in August and a 1/12 chance it was delivered in May.

Definitely not 50/50.

Switching increases the chances of winning by a factor of 11.

After all, when it can rain or shine the weather forecaster takes into account the probability of each.

She does not simply say: "Two possibilities, so I guess that means a 50% chance of rain!"

[Whubbsie]

far as I can tell it comes down to 2 things maths and logic.
pure maths means 11/12 of chosing correctly or 1/12 because you always have to factor in the other months.

logicly after all the months are striked out you have a 50/50 chance as you only have two options....
this is a chicken and the eggs senario ... now shut the **** up and look at the hot girlies next to cars....


PS I just got home from the Telsra small business awards I'm drunk and hungry...

[Dubya]

If it were 50/50 then if the owner made the bet with 12 people who each chose a different month then without switching 6 would win! But this cannot be as only one month is correct.

In reality, if no one switched, 11 would lose and one would win.

That is the reality and, of course, it proves the theory.

But if they each switched, 11 would win and only 1 would lose which also proves the theory.

Scotty, team_v, Rocket36 et al ... Anyone in need of further proof that it is not 50/50 between the two remaining options and that the odds are 1/12 and 11/12 and so favour switching 11:1?

Just as in Monty Hall they favour switching 2:1 (67% over 33%).

[Dubya]

Wow this is still going? This thread is going around in circles.

There still appear to be some people under a misapprehension.

I don't mind coming up with new ways of explaining why there is not an equal chance of the two remaining options being the winning choice.

Are you able to explain it any better so people understand or are you still in the 50/50 camp?

[maca]

I'm not in any "camp".

I'm just making simple observations from what I believe is happening in this thread. Not hating or anything, but it seems the same information has been reposted here about 11ty times.

[Dubya]

I'm not in any "camp".

I'm just making simple observations from what I believe is happening in this thread. Not hating or anything, but it seems the same information has been reposted here about 11ty times.

A fence sitter?

Either way, it seems you have no interest in this thread and no view on its subject so why concern yourself by posting your opinion of a thread in which you have no interest and nothing to contribute?

Do you understand the Monty Hall dilemma? Happy to hear your reasoning if you want to make a contribution.

Otherwise, why nit ignore it like the other 5000 members who are uninterested?

[maca]

A fence sitter?

Either way, it seems you have no interest in this thread and no view on its subject so why concern yourself by posting your opinion of a thread in which you have no interest and nothing to contribute?

Do you understand the Monty Hall dilemma? Happy to hear your reasoning if you want to make a contribution.

Otherwise, why nit ignore it like the other 5000 members who are uninterested?

This might come as a shock to you, but I'm genuinely interested in trying to figure our what the feck this thread is about. I asked another user last night when I saw him and he explained it to me, but it still makes no logical sense to me.

If you have three doors and behind one of those doors, you have a car. You are then asked to choose which door has the car behing it, which means you have a 33% chance of selecting the correct door. If one of those doors were removed which left only two doors to choose from - one having the car behind it, that would leave you with a 50% chance of selecting the correct door only if you can be guaranteed the car was not behind the door which was removed from the choice.

[Buller_Scott]

If one of those doors were removed which left only two doors to choose from - one having the car behind it, that would leave you with a 50% chance of selecting the correct door only if you can be guaranteed the car was not behind the door which was removed from the choice.

pretty straightforward, right?

dubya, i tried to pm you last night after your multiple pms to me regarding this thread, simply to reiterate things that not only have i said in the monty hall thread, but also this thread, and that i will be removing myself from the discussion.

i notice you've pm'd me twice again today- but i could not respond, because apparently your inbox is full. so i'll just say it here- you have typed much, you've discussed my misinterpretations of numbers etc etc in instances where i was being sarcastic in illustrating the shortcomings in using the number 11/12 to describe the odds one faces when choosing ONE of either may, or august. i apologise, but nothing you have posted here, nor in the numerous pm's to me, have convinced me to ''switch sides'', so to speak.

with all due respect, and i dont want to sound ''aggressive'' or confrontational when i ask this, but is it safe to assume that this thread wont actually end until people just shut the **** up, and agree with you? i understand that you're convinced of your reasoning, and will work to ensure that myself and others, are convinced as well.

im sorry- i cannot agree with you, and the numbers 11/12, when faced with two choices [may or august], look just plain silly IMO. that's my last word in the matter, and it's final.

so yeah, take it easy, and dont get too worked up over it- there'll be other discussions on VWWA in the future

cheers,

scotty.

p.s. re your pm- in the monty hall dilemma thread, it was established from the outset that you MUST have a failing door opened first. there was some discussion, and it was made clear to all involved that there IS a game show host, he DOES know which door houses what, and his sole functions in the riddle are 1. to allow the contestant to select one door to open; 2. regardless of whether the contestant chose a goat or the gti, the host then opens A door which houses a goat; and 3. to offer the contestant the opportunity to switch, . so yes, you MUST have a failing first choice- there was never any probability regarding the first door, as it was a rule in the riddle that the game show host MUST reveal the first door to open as housing a goat.

[Whubbsie]

the one on the right, is a tranny surprise.........

This is a recurring issue with you.... it needs to stop or you are going get me paranoid..... though if its stops me from being raped by a tranny maybe its worth it.... thats the real question.....

we can call it the 'Tranny Surprise Dilemma'

Dubya whats my chances of calling correcltly on a coin toss? (i stipulate a 2 sided coin, not a 12 sided one where 10 sides are taken away because some time traveller comes back from the future and tells you those 10 aren't correct)....

50/50 <---- you see that, you get that, do you now understand why people are siding on 50/50.

only on an exam question or if you are rainman would you consciously factor in all the doors and know to swicth to give yourself better odds.

and if i was rainman id be off at the casino counting cards at blackjack with tom cruise making big bucks and trying not to tard out.

[maca]

Say I had a regular door that I could either open or close.

What are the odds of either? 50% chance I'll open it and 50% chance I'll close it. Now, what if my primary reason for opening the door is to walk through it? That would change the odds, no? I would be opening the door to go through it. But we all know that I wouldn't fit through if I only opened the door by 10cm.

What are the odds of me opening the door wide enough to ensure I will fit though it? The 50/50 chance of me opening/closing it is still present, but with the added technicality of me completing my goal (walking through the door).

[Maverick]

You're my hero again, Whubbsie. You've proven my point exactly.

There are so many varying factors when it comes to probablity, there can never be a definite answer.

Was that an ordinary automatic door, an ordinary door with a doorman or a bog standard household quality open it yourself door?

And what if the power is out, the doorman is asleep or someone opens the household door at the same time that you arrive?

[maca]

Was that an ordinary automatic door, an ordinary door with a doorman or a bog standard household quality open it yourself door?

And what if the power is out, the doorman is asleep or someone opens the household door at the same time that you arrive?

You're hurting my brain!!


Call me stubborn or whatever, but I just can't move away from how it's a 50/50 chance. I can appreciate what Dubya's told us many times in different ways, but I just can't shake the simplicity of this whole equation.

[Treza360]

Right. Well done to those who kept on topic. To those that didn't you're lucky I didn't hand out the bans but hey I'm in a good mood.
As with the last thread and last time, once again the correct option is not to switch and your choice does not miraculously become 50/50 as you have prior knowledge and choices. If you don't get the maths behind it that's ok some people just aren't inclined that way. Just don't for a minute think that you're right for a 50/50 chance because you're not end of story. If you wan't to discuss this topic further go and join a science/maths/statistics forum.
That is all.
Cheers,
Trent