Miscellaneous Puzzles

Word and grammar games and other miscellaneous entertainments that people use to pump up their post count use to have fun.
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Fallout_Monkey
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Re: Miscellaneous Puzzles

Postby Fallout_Monkey » Fri Jul 10, 2020 7:50 am

How was May eliminated again? I get Jun that on makes sense. But after you eliminated the 19th there were still two dates that had the same number as dates in Jul and Aug.
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Lord Foul
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Re: Miscellaneous Puzzles

Postby Lord Foul » Fri Jul 10, 2020 8:43 am

Lord Foul wrote:Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is.

Cheryl gives them a list of 10 possible dates. May 15, May 16, May 19, June 17, June 18, July 14, July 16, August 14, August 15, August 17. Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively.

Albert says: “I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too.”

Bernard says: “At first I didn’t know when Cheryl’s birthday is, but I know now.”

Albert says: “Then I also know when Cheryl’s birthday is.”

So when is Cheryl’s birthday?

The only way that Albert can know that Bernard doesn't know is that he knows it isn't either of the unique dates, the 18th or 19th; all other dates have multiple months, which Bernard could not know. The only way he can know it isn't the 18th or 19th is because he knows it isn't either May (19th) or June (18th).
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Fallout_Monkey
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Re: Miscellaneous Puzzles

Postby Fallout_Monkey » Fri Jul 10, 2020 9:12 am

Ah I get it now, it's one of those perfect logician things. Because Albert spoke first(and said what he said) without any input from Bernard that's how Bernard would know it isn't may. Where as my answer of Aug17 would be correct if Bernard had stated first that he couldn't figure it out before they had the same exchange.
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Lord Foul
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Re: Miscellaneous Puzzles

Postby Lord Foul » Fri Jul 10, 2020 1:09 pm

Fallout_Monkey wrote:Ah I get it now, it's one of those perfect logician things. Because Albert spoke first(and said what he said) without any input from Bernard that's how Bernard would know it isn't may. Where as my answer of Aug17 would be correct if Bernard had stated first that he couldn't figure it out before they had the same exchange.

I don't think that would affect the outcome, so Aug 17 is still wrong even after Albert admits he doesn't know. The extra bit of Bernard stating first just replicates the first part of "Bernard says: At first I didn't know". It doesn't add anything new to the chain of logic.
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Fallout_Monkey
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Re: Miscellaneous Puzzles

Postby Fallout_Monkey » Fri Jul 10, 2020 1:44 pm

Lord Foul wrote:I don't think that would affect the outcome, so Aug 17 is still wrong even after Albert admits he doesn't know. The extra bit of Bernard stating first just replicates the first part of "Bernard says: At first I didn't know". It doesn't add anything new to the chain of logic.


You're right it doesn't add anything, it would take away. If the conversation were to play out like this:

Bernard says: "I don’t know when Cheryl’s birthday is"

Albert says: “I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too.”

Bernard says: “I know now when Cheryl’s birthday is.”

Albert says: “Then I also know when Cheryl’s birthday is.”

May 15 May 16 May 19
Jun 17 Jun 18
Jul 14 Jul 16
Aug 14 Aug 15 Aug 17

Bernard couldn't eliminate May and know the answer if he spoke first because May 19th would be off the list and thus Albert's statement couldn't eliminate the two dates in May. Thus if the conversation played out like above Aug 17 would be the date because that is the only one that could.

But anyway I didn't use the right logic and didn't get it right so we can move on.
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Lord Foul
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Re: Miscellaneous Puzzles

Postby Lord Foul » Fri Jul 10, 2020 2:23 pm

Ah, I see what you mean now. That's an interesting twist. Logic is a weird thing sometimes. :lol:
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Arbuthnott
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Re: Miscellaneous Puzzles

Postby Arbuthnott » Fri Jul 10, 2020 5:07 pm

Fallout_Monkey wrote:Is it Aug 17?

because Bernard didn't say anything Albert can eliminate the unique dates of May 19 and June 18.
This leave 2 dates in may, 1 in june, 2 in July and 3 in Aug. Which since Albert says Bernard can't figure it out means June can't be the month. This leaves Bernard with 2 14s, 2 15s, 2 16, and 1 17 so the number had be 17 for Bernard to figure it out


When I read this, it made perfect sense to me, and I couldn't work out how both our answers seemed right, even though there could obviously only be one right answer. It's amazing that a little detail like Bernard speaking first can lead to an entirely different answer.

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Arbuthnott
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Re: Miscellaneous Puzzles

Postby Arbuthnott » Fri Jul 10, 2020 5:30 pm

Okay, here's a two parter:

1) Dave has a six-shooter revolver and a single bullet, and he makes a bet with Kirsty that he will shoot a glass bottle on an even number. He puts in the bullet, spins the chamber and fires, but no bullet comes out. He gives Kirsty the choice of whether or not he should spin the chamber before the second shot. Should Kirsty tell him to spin the chamber?


2) Same situation, but Dave has two bullets, which are put into consecutive chambers. Should Kirsty tell him to spin the chamber after nothing comes out of the first shot?

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Fallout_Monkey
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Re: Miscellaneous Puzzles

Postby Fallout_Monkey » Fri Jul 10, 2020 5:43 pm

I think yes in the first case because a spin returns the probably back to 1 in 6 chance from a 1 in 5 chance

I'm not sure in the second case as it's 1 in 3 vs 2 in 5

Edit: I think don't spin on the second case because the odds of an empty slot after an empty slot are one in three(or is it 4)
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Lord Foul
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Re: Miscellaneous Puzzles

Postby Lord Foul » Fri Jul 10, 2020 6:13 pm

1) Yes, spin the chamber. 1 in 6 chance is less than 1 in 5 so better to randomise it again.

2) No, do not spin the chamber. Because they are in consecutive chambers, the first shot must have been one of four consecutive empty chambers, only one of which is then followed by a loaded chamber. That gives a 1 in 4 chance on the next shot which is less than the 1 in 3 from a randomised shot.
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