# Logic puzzle

#### tribdog

leto said:
I disagree. By removing the 999998 doors, the chance of the door you didn't pick being the door increases. The door you did pick could not be removed, and is therefore less likely to be the prized door.
correct. in the million door scenario the chances of the door you picked being the correct door is 1 in a million, therefore wouldn't the chance of the other door being the correct one be 999999 in a million? The point being it is always better odds to make the switch in a situation like this.
another way of looking at it is this: after you make your first choice you are given the option of keeping your door or taking all 999999 of the other doors.(which is the same thing as taking one door that may be right and throwing out 999998 wrong ones) Do you keep your 1 or take all 999999 of the others?

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#### marqq

leto said:
I disagree. By removing the 999998 doors, the chance of the door you didn't pick being the door increases. The door you did pick could not be removed, and is therefore less likely to be the prized door.
The problem allow us to eliminate only one door...From 3 doors or from 100000000 doors....we are able to remove only one door...

#### marqq

leto said:
There are three possibilities with the first weigh. Either it tips to the left, right or stays level. I accounted for all three of these.

Edit:

I think you are assuming I label them l1-l4 and h1 - h4 because I assume I know this. I only label them as such so that I know later that, if one of them is the odd ball, they have to follow that pattern. A ball that was on the heavy side will never be the lighter odd ball.
sorry ... i missunderstood your "l-f" definition...i was tired and i thought you ment left-right...and swiching the balls, an left becomes right and viceversa.....therefore i missjudged your solution....i am deeply sorry....your answer is as corect as it can be..... i'm really sorry about that

#### marqq

Another one..A funny one

The mother is 21 years older than the son.In 6 years, the son will be 5 times younger then his mother.Question: where is the father now?

#### pig

enjoying himself :)

#### marqq

pig said:
enjoying himself :)
you are closer to the answer than you imagine

#### pig

marqq said:
you are closer to the answer than you imagine
i got the answer, that's why i wrote that ;)

#### verty

Homework Helper
Here's an easy one. See if you can solve this riddle in under 30 seconds...

Two Russians are walking down a street. One Russian is the father of the other Russian's son. How are they related?

#### Chen

Husband and wife? In second thought, I don't know how things work in Russia so my answer would be "they had sex".

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#### Chen

tribdog said:
no I don't think that is correct. its close, but not right. What if there are a million doors and after you choose Monty Hall/Bob Barker throws out 999998 of the bad doors and says it's either the one you chose or this one? do you think it is still a 50/50 chance then?
Ahh yes, why not? Because Bob says "it is either the one you chose or the other", which implies that one of the doors is the right one. He does not ask "would you like to change your pick now", which doesn't necessarily mean one of the doors is the right one. So yes, your chances would be 50/50.

#### marqq

Another funny one

We have a driver who has to make the distance between A and B in his own car...He drives the 1st 3rd of the distance with 40 km/h (he was reall calm) then he becomes angry and drives the 2nd 3rd with 120 km/h...then it calms down and asks himself what is the speed that he should use for haveing a decent average of 90 km/h

I'll ask you to try (before starting to calculate) an aproximation by intuition, and then make the difference to see it it was a small or a huge error :tongue:

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#### Chen

Is 120 km/sec a typo or did you really mean that? If it's a typo he should drive at 110 km/h, if it's not... I don't think he can reach an average of 90 km/h after driving at ~400,000 km/h.

#### marqq

If it's a typo he should drive at 110 km/h, if it's not...
sorry
I was thinkin at smth else
120 km/h
And about the 110km/h you are wrong !Hint : make an ecuation

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#### Chen

I did...

$$90 = \frac{40 + 120 + x}{3}$$

$$x = 110$$

#### marqq

1/90 = 3(1/40 + 1/120 + 1/x)

#### Chen

You do realize, marqq, that the solution to that equation is negative?

#### marqq

is not negative...is just the infinite x

#### pig

marqq said:
He is located inside the wife, at least a certain part of him.. I didn't want to spoil since it's simple but funny :)

As for the driver.. If t is time in which he would have to make the whole trip for his average to be 90 km/h, he spent exactly t on the first two thirds of the trip. Which means he would have to make the remaining 1/3 in 0 hours, going infinitely fast :)

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#### marqq

pig said:
He is located inside the wife, at least a certain part of him.. I didn't want to spoil since it's simple but funny :)

As for the driver.. If t is time in which he would have to make the whole trip for his average to be 90 km/h, he spent exactly t on the first two thirds of the trip. Which means he would have to make the remaining 1/3 in 0 hours, going infinitely fast :)
Well done Pig

#### marqq

i'm inside of an imaginary cyrcle on which a shark swims inteligently (he can change the direction or he may stop but he can't enter the cyrcle) 4times faster then i do. Can I exit the cyrcle without been cought by the shark?

#### marqq

Btw ...who-s the phorum administrator? i have a problem with my avatar and my signature :)

#### jammieg

Damn those true or false questions!

True or false, what is your name?

#### marqq

off topic. erase your post :)

#### Angel Loupe

Cannibals & Missionaries

Taken Hurkyl's legend:
l l=river < >=canoe C=Cannibals M=Missionaries

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C MMM l< C > l C
CC MMM < > l l C
MMM l<C C>l C
MMM l l < > CCC
MMM l< C > l CC
C MMM < > l l CC
C M l<MM>l CC
C M l l < > CC MM
C M l<CM>l C M
CC MM < > l l C M
CC l<MM>l C M
CC l l < > C MMM
CC l< C >l MMM
CCC < > l l MMM
C l<C C>l MMM
C l l < > CC MMM
C l< C >l C MMM
CC < > l l C MMM
l<C C>l C MMM
l l < > CCC MMM