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alien2
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 Which door?   « on: Dec 18th, 2017, 8:32pm » Quote Modify

There are three identical adjacent doors. One is locked, another is open and the remaining one is either locked or unlocked. You are given a key that you are allowed to use one time, after which you are allowed to open, if possible, all three doors (by turning all three doorknobs). Your goal is to try to open all doors, behind of which there are three prizes; otherwise, you might turn out empty-handed, like me. Calculate the odds of receiving a prize. Btw, I suck at math so don’t ask ME ‘bout it. But, have fun.

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Riddle modified in order to clarify a few things.

 « Last Edit: Dec 21st, 2017, 10:04pm by alien2 » IP Logged

dudiobugtron
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 Re: Which door?   « Reply #1 on: Dec 21st, 2017, 11:04am » Quote Modify

Can you turn each doorknob more than once?  Or once only?
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alien2
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 Re: Which door?   « Reply #2 on: Dec 21st, 2017, 11:09am » Quote Modify

I see. You answer a question with a counter-question. You are not a psychiatrist, are you?! FORWHY, if you are, and I say... IF, I will... ask for a session, politely, and tell you that, in my opinion, you can do with doorknobs anything you like.
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towr
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 Re: Which door?   « Reply #3 on: Dec 21st, 2017, 12:33pm » Quote Modify

If you get a price for every door you manage to open, then I'd say there's a 5 in 6 chance you'll get at least one price; a 1 in 2 chance the uncertain door is closed multiplied by a 1 in 3 chance you close the open door.
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Wikipedia, Google, Mathworld, Integer sequence DB
Vondell
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 Re: Which door?   « Reply #4 on: Dec 21st, 2017, 12:39pm » Quote Modify

Heh.  The answer does depend on the rules.
Is there a guaranteed prize behind at least one of the doors?
Are the prizes behind the doors, or given out contingent upon opening the doors?
Will the key work in any of the locks?
If allowed to test the doors, then...
One door is already open and you would be able to see whether or not there is a prize
or
One door is already open...2 to go
which then depends on the other 2 doors.
Those 2 doors can be tested to see if either one is already unlocked.  If one is already unlocked...bonus!...and the chance of getting a prize is 100% provided that the key works in any of the locks.
If both remaining doors are locked, and there is a guaranteed prize behind one of the doors and is not behind the already open door then you have a 50% chance of getting said prize.
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Why is it that people ask for my two cents worth, and then only offer me a penny for my thoughts?
That deal sucks!
Grimbal
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 Re: Which door?   « Reply #5 on: Dec 21st, 2017, 1:33pm » Quote Modify

You always win these 3 prices:
1. a lovely key
2. the happiness of being recognized a trusted member of the community by being entrusted the key to their most precious belongings.
3. the joy of running away with all their valuables.  As it happens, all 3 doors lead to the same room.
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alien2
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 Re: Which door?   « Reply #6 on: Dec 21st, 2017, 9:58pm » Quote Modify

It is Christmas time. There are three prizes. Don't be a stingy Santa Claus, you hear? And buy your wife an ice-cream.

p.s. (I am modest) After posting a googol riddles by using Google Chrome, I, alien2, have concluded, that I am but . . . a universe; which, of course, proves that, multiverse is not science fiction rather science fact. And now, I'd like to receive the Nobel Prize in Riddles 2017. Alright!
 « Last Edit: Dec 21st, 2017, 10:54pm by alien2 » IP Logged

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