Thats it, SixOfSpades. The reason why its 66 % and not 50 is that you know that that door has been left closed BECAUSE the quiz master didnt want to show the gift. The example of the 1000 doors is so clear. After discarding 998 doors, you have door A (first choice) and door B (the one that the quiz master left closed). Id bet that door B has the prize because the quiz master decided to leave it closed, because he CHOSE that door between 999 doors. You dont have to think that maybe he chose that door randomly because you already had pciked the right one, thinking that wouldnt be clever i think because the chances of you picking the right one the first time are 1/1000, so 999 times out of 1000 the quiz master would have POINTED you the right door.

The odds would be 50/50 if, after the quiz master discarded the doors, a NEW person appeared and had to choose between the 2 doors, without knowing which one is the one that the master decided to keep closed.

I think its clear now, but if you want me to reason it further, just ask ;) . Im gonna sleep now, see ya

Ummmmmmm..... I feel silly. I didn't read the entire thread before spouting my opinion. I didn't realize the Game Host HAD to open an empty prize door. This throws a monkey wrench into the works as HIS choice isn't random either. Exactly how much this affects the natural 50/50 probability of the remaining two doors is a matter for statisticians to debate. Since he KNOWS which door the prize is behind, the door he DIDN'T pick has a higher probability of being the one with a prize in comparison to your COMPLETELY RANDOM guess. Think of it as him having an inside tip that you don't have.

And last, look at this example: you have 1000 doors, the prize is on door #1000 ok ?

Now imagine that you are given 1000 chances:
first time, you choose door 1, and after the master opens all except number 1000, you switch your choice, and you WIN.
same for number 2, number 3.... till number 999.
last time, you choose number 1000. after the master opening all of the rest except a random one, you switch your choice and you LOSE.

You would have won 999 times out of 1000. I think its transparent as water now :D

<blockquote>quote:</font><hr>Originally posted by Sir Kenyth:
Ummmmmmm..... I feel silly. I didn't read the entire thread before spouting my opinion. I didn't realize the Game Host HAD to open an empty prize door. This throws a monkey wrench into the works as HIS choice isn't random either. Exactly how much this affects the natural 50/50 probability of the remaining two doors is a matter for statisticians to debate. Since he KNOWS which door the prize is behind, the door he DIDN'T pick has a higher probability of being the one with a prize in comparison to your COMPLETELY RANDOM guess. Think of it as him having an inside tip that you don't have.<hr></blockquote>

Exactly Sir Kenyth! That is what I have been trying to say for quite some time now! I posted the riddle yet no one seems to want to beleive me about the answer. Well they can disagree with me, as long as they don't mind disagreeing with the majority of the mathematics community.

Also, just a quick one Six. IT DOESNT MATTER HOW MANY DOORS YOU HAVE NOW (not shouting - just emphasis). What matters is which door you chose and which door the quiz master chose. Ertai explained it much better than me, read his posts. But basically it makes more sense if you talk about 100 hundred doors, and so on.

<font color="red"> If there are 100 doors, and 1 is right- first choice- 1 useful option, 100 posible options. Chnaces o fu getting it right- 1/100. Then the quiz master gets rid of all but 2, the pne uv got and another one. ONE OF THESE IS RIGHT. there are 2 possible choices and 1 useful options. 50% chance of getting it right.
Yes, logically it sounds like it shouldnt change, and that logic works, but this must be the correct answer because it is mathematicaly justified- IN a maths problem, u must use maths all the way through.
So basically- we were all wrong. There are possible answers. If presented as a math problem its 50-50, if presented as a logic problem u should change because of what ertai said...
so can we have a puzzle that everyone will agree on?? \/\/3|_3 |\|3|/3|2 63+ 4|\| 46|233|\/|3|\|+ 0|\| +|-|][5!!

Yay.....we seem to have reached something at least resembling an agreement. Here's hoping we're done....

And hey! That means it's time for......ANOTHER RIDDLE! Don't worry, though, this one's just trivia.

Without looking up the answer, how many of you (us) can name all 13 Dwarves who accompanied Bilbo Baggins in The Hobbit? Just off the top of your head.
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This blank space is to remind you to hit the 'Reply' button now, before looking at other peoples' answers.
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Thorin, Bifur, Bombur, Oin, Gloin, Balin, Dwalin, Fili, Kili, Bofur

uhhhh

EDIT: Dori, Nori, Ori.. I knew about these 3 but I wasnt sure if they were correct..

<font color="gold"> Havent read lord of the rings yet... or the hobit for that matter... So could u post a riddle that we can solve from the information given?? Trivia is kind of hard to get if u have never been exposed to anything which would help u answer it... not that u could have known before this. </font>