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

**Dubya** · 29-06-2010, 08:57 PM

Imagine someone unknown to you drove up in their Mark V Golf and said "I'll offer you odds of 10:1 that you cannot guess the month in which I took delivery of my Golf."

Even though your chances of picking the right month are only 1/12 (the year is not required), you guess May.

The person then says, let me tell you 10 of the months in which I did not take delivery of my car.

He then tells you every month of the year except August and May.

You now know the car was delivered in either August or May.

He then asks, "Would you like to stick with your original choice of May or switch to August?"

A group of onlookers has gathered.

People are yelling advice.

One, named Buller_Rock_v, is particularly vocal and says: "Stick with your initial choice! There are only two possible months now and only two choices; you have a 50/50 chance of winning now. You'll kick yourself if you switch and are wrong!"

Another person, Hawkie, says, "There was a 11/12 chance of you picking the wrong month in the first place. This has not changed now that you know 10 of the months that are wrong. There is an 11/12 chance that if you switch you will win, even though to some it looks like a choice between just two dates and a 50/50 chance!"

You hesitate.

There are only two options now. With only two months to choose from, it looks like 50/50.

But is it?

What would you do?

**whiteVR6** · 29-06-2010, 09:16 PM

check the rego label, cars should be delivered within 7 days of being registered

**Whubbsie** · 29-06-2010, 09:16 PM

havent we already been through this?

**dylan8** · 29-06-2010, 09:18 PM

Not this again, does my head in after a full on day at work...
Couldnt it be posted on the other threads? or does everyone else enjoy it that much...

**team_v** · 29-06-2010, 09:19 PM

This was done to death before.
with the 3 doors to win a GTI Monty Hall Dilema.

In the end, you cannot consider the original chance of winning as the variables have changed and you can make an educated decision.
Sure, you could choose one of the months that they have already discounted but why would you.

**PassatB6** · 29-06-2010, 09:39 PM

Originally Posted by Dubya

Imagine someone unknown to you drove up in their Mark V Golf and said "I'll offer you odds of 10:1 that you cannot guess the month in which I took delivery of my Golf."

Even though your chances of picking the right month are only 1/12 (the year is not required), you guess May.

The person then says, let me tell you 10 of the months in which I did not take delivery of my car.

He then tells you every month of the year except August and May.

You now know the car was delivered in either August or May.

He then asks, "Would you like to stick with your original choice of May or switch to August?"

A group of onlookers has gathered.

People are yelling advice.

One, named Buller_Rock_v, is particularly vocal and says: "Stick with your initial choice! There are only two possible months now and only two choices; you have a 50/50 chance of winning now. You'll kick yourself if you switch and are wrong!"

Another person, Hawkie, says, "There was a 11/12 chance of you picking the wrong month in the first place. This has not changed now that you know 10 of the months that are wrong. There is a 11/12 chance that if you switch you will win, even though to some it looks like a choice between just two dates and a 50/50 change!"

You hesitate.

There are only two options now. With only two months to choose from, it looks like 50/50.

But is it?

What would you do?

The answer is you should switch. Yes, it is the Mont Hall dilemma but the issue is that our logic tells us its a 50:50 chance while maths tells us that this is not actually true. Its one of those cases where our understanding of the world is wrong but we find it hard to understand how it could be. Like an optical illusion.

In fact you have 11 times the chance of getting it right by switching.

**team_v** · 29-06-2010, 09:44 PM

Originally Posted by PassatB6

In fact you have 11 times the chance of getting it right by switching.

You have a better chance of getting it right by switching if you still include the other months that have already been discounted as an option to choose.
However you already know they are wrong so your choice is down to 2 so the odds for a normal person are 50:50 but the odds for a person who doesn't care about winning and considers the other doors as a valid option are 11:12

**Dubya** · 29-06-2010, 10:36 PM

Originally Posted by team_v

You have a better chance of getting it right by switching if you still include the other months that have already been discounted as an option to choose.
However you already know they are wrong so your choice is down to 2 so the odds for a normal person are 50:50 but the odds for a person who doesn't care about winning and considers the other doors as a valid option are 11:12

Glad to see you now see the merits of switching after proclaiming no benefit in switching in the Monty Hall game because you believed the odds were 50:50 no matter which of the remaining two closed doors you chose.

But now you say the odds would be 50:50 for a "normal person" and 11:12 for someone who "doesn't care about winning".

Somehow the characteristics of the person affect their odds?

Wouldn't the probability of guessing right be 1/12 if one stuck with the original choice and 11/12 if one switched?

Just like they are 1/3 (for the initial choice) and 2/3 (for the only remaining choice) in the MH game?

**maca** · 29-06-2010, 11:09 PM

Rego plates normally help. E.g. we're up to ###R** atm and say the car was delivered around last Semptember/October, it'd have ###L**. I mean, that's if it hasn't been reregistered.