The Singapore Logic Puzzle

[axordil]

The Singapore Logic Puzzle (which is designed for 14 and 15 year olds in math competitions, not 5th graders as originally stated in some venues) reminds me a lot of the old GRE reasoning section. I loved that stuff.

[yovargas]

What the......how is that even......I mean......what???

[axordil]

It looks a lot hairier than it actually is. I made things more obvious by dropping the dates into a spreadsheet so the cells lined up by month one way and date the other.

Apparently how one interprets Albert's first statement can make a difference in the outcome, too.

[yovargas]

But all Albert says is "We don't know." How the hells does Bernard respond to that with "Now I do"?????

[Inanna]

Don't look at it as a conversation, Yov, look at it as a logic statement.


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Please bear with my typos & grammar mistakes. Sent from my iPhone - Palantirs make mistakes too.

[Inanna]

So take Albert's statement to
Mean that neither Albert nor Bernard know the birthday. Then you look at the options given.


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Please bear with my typos & grammar mistakes. Sent from my iPhone - Palantirs make mistakes too.

[yovargas]

Ooooooohhhhhhhh. I misunderstood the setup, I think I get it now!
Is this it?

Hidden text.

June 17

[axordil]

Nope

[yovargas]

[JewelSong]

I went right to look for the solution, I could never do those kinds of puzzles. And even when I read the answer, I still didn't really get it. My brain isn't wired that way..

I can't do Sudoko either...not even the easiest ones,


Sent from my iPad using Tapatalk

[Frelga]

Well, I applied the correct logic but did the date matrix wrong on the first try. So basically I solved it twice.

I am not great at these, but this one is not particularly difficult.

[yovargas]

I gave up and looked at the answer. My logic was roughly on the right track but got tripped up on a couple things.
I'm gonna disagree with Frelga and say that that was plenty tuff stuff.

[Dave_LF]

There are quite a few of these logic puzzles where the key to getting the correct answer is to draw conclusions from another person's ignorance. Here is another one.

Three wise men are told to stand in a straight line, one in front of the other. A hat is put on each of their heads. They are told that each of these hats was selected from a group of five hats: two black hats and three white hats. The first man, standing at the front of the line, can’t see either of the men behind him or their hats. The second man, in the middle, can see only the first man and his hat. The last man, at the rear, can see both other men and their hats.

None of the men can see the hat on his own head. They are asked to deduce its color. Some time goes by as the wise men ponder the puzzle in silence. Finally the first one, at the front of the line, makes an announcement: “My hat is white.”

He is correct. How did he come to this conclusion?

[axordil]

I attached a jpg of my method with the spreadsheet.

Now to see if it works for hats.

[axordil]

Hidden text.

So the first guy in line announces his answer based on neither of the other two being able to tell. For this to be the case, the last one in line, who can see the other two, must have insufficient information. Given the hat breakdown, that means the first two can't both be wearing black, since then he'd know he had a white hat on. However, as far as other two go, they only know that either the first or the second might have black and the other white, or they might both have white. The second guy knows this as well from the third guy's silence—he is wise after all—and so how can he have insufficient information too? Well, if the first guy had a black hat, given what the second guy knows about the third guy's deductions, then the second guy would have to have a white hat, since the only possibilities are b/w, w/b, and w/w. Since the second guy doesn't know either, it can only mean the first guy has a white hat.

That one was actually simpler--I didn't need the spreadsheet

[Faramond]

What I love about the Singapore Logic Puzzle is all the pettiness and spiteful behavior and interpersonal drama.

What is with Cheryl, anyway? Why can't she just give a straight answer? Why does she have to give half the answer to one boy and half to another boy like she's sending out a coded WWII message? Is it part of some devious long con? Some sort of contest to see who gets to take her to the prom?

And why do Albert and Bernard hate each other so much? They could have cooperated from the beginning, but instead they jealously held their vital bit of birthday information back. And then the smugness, the taunting, the boasting!

Albert: I don't know it, but you don't know either! Ha ha ha!

Bernard: Suck it, Alturd, because even though I didn't know, now I do know, all because you opened your fool mouth! I glory in my superior knowledge!

Albert: Well I know it too now, Bernads, so you can suck it instead, and the glory is all mine!

And Cheryl just smirks at the two fools, because of course she was lying the whole time. Her birthday is October 14, and she's going to the prom with Darla. As if she would tell those petulant smug immature brats anything about her birthday!

[yovargas]

Humans: The Unsolvable Logic Puzzle.

[Primula Baggins]

Faramond, dammit, just . . .

[Inanna]

Faramond - oh man. ACtUALLY lol!


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Please bear with my typos & grammar mistakes. Sent from my iPhone - Palantirs make mistakes too.

[Frelga]

I was looking for a like button, and I'm not even on Facebook.

What I find curious about both this and the three-hat puzzles is that their solution is dependent on each of the solvers being assured that everyone else is making accurate deductions, rather than just standing there wondering when they can take the stupid hat off.

I came across this one on a Russian feed. Skipping the story about two wise men and an obnoxious ruler, it boils down to two numbers greater than 1 and less than 100. Wizard A is given the product of multiplication (x*y), wizard B the sum (x+y).

A: I don't know the numbers
B: I knew you wouldn't know
A: Then I know
B: Then I also know.

What did the ruler had for breakfast?

OK, no, what were the numbers?

Edited to fix the puzzle.