Daily puzzles/problems.

[billl]

I would not be at all offended if someone else were to post a new one. (Actually, Mick got the correct answer... so he's equally on the hook.)

I will put something up eventually though, if nobody has thought of any other good ones by then.

[prendrelemick]

How about if Mark leaves Heathrow at 06.00 oclock and lands in New York at 08.00. How long is he in the air?

[MarkBastable]

How about if Mark leaves Heathrow at 06.00 oclock and lands in New York at 08.00. How long is he in the air?

It depends how many people under five you're travelling with. A few years back, when Nell and Grace were four and two respectively, I seem to remember being on a flight for several days.

[MarkBastable]

Also taken from the Net, and a variation on the previous one...

Three women - one of whom we'll call Intelligentsia, because she has a talent for logic problems, and is therefore an absolute blast at extended wine-bar lunches - are sitting in a circle. They are blindfolded and told that a spot of either red or white will be put on each of their foreheads.

A red spot is then put on each of their foreheads.

The blindfolds are removed and they are told to raise their hand if they can see any red spots. All three raise their hands.

They are told to lower their hands if they know what colour spot they have on their own forehead.

Intelligentsia ponders for a moment, and then lowers her hand.

What has she figured out that the other two haven't?

[billl]

uh, uh..

[prendrelemick]

All those wine bar lunches paid off, she can smell the Pinot Noir on her forehead.

[MarkBastable]

Because precision of language is so important in these things, I've edited the problem slightly.


...just as a clue - the other two women are pretty bright too. But not as bright as Intelligentsia.

[billl]

Oh, one of the others has a white spot on their head. So the OTHER (3rd) woman must've seen a red spot on Intelligentsia's head.

[MarkBastable]

Oh, one of the others has a white spot on their head. So the OTHER (3rd) woman must've seen a red spot on Intelligentsia's head.

No, they all have red spots.

[billl]

It has something to do with the plural "spots"?

[billl]

How about if Mark leaves Heathrow at 06.00 oclock and lands in New York at 08.00. How long is he in the air?

Seven hours?

[MarkBastable]

It has something to do with the plural "spots"?

Nope - there's nothing tricksy about it. The problem is just as it appears.

[billl]

But if Intelligentsia can see a red spot on each of the other women's heads, then it doesn't matter if she has a red or white spot--the other women would each see (at least the one) red dot. How could she be sure she didn't have a white dot?

Is it because the others would've known that THEY would both have a red dot if she had a white dot and didn't announce that she was sure that she had a red dot? And so the pause means no one can be sure, which means: three red dots...?

I see, then! So all three are smart enough to figure it out, if the given the visible dots are sufficient--but she is the first to figure out that she can, on account of their uncertainty, figure it out even when the visible dots had left some ambiguity...

[MarkBastable]

If the others are logical, Intelligentsia can be completely certain she has a red spot - unambiguously.

But you're damn close (in fact, you might be right, but I'm not certain about the phrasing).

But if Intelligentsia can see a red spot on each of the other women's heads, then it doesn't matter if she has a red or white spot--the other women would each see (at least the one) red dot. How could she be sure she didn't have a white dot?

Is it because the others would've known that THEY would both have a red dot if she had a white dot and didn't announce that she was sure that she had a red dot? And so the pause means no one can be sure, which means: three red dots...?

I see, then! So all three are smart enough to figure it out, if the given the visible dots are sufficient--but she is the first to figure out that she can, on account of their uncertainty, figure it out even when the visible dots had left some ambiguity...

[prendrelemick]

Seven hours?

Is it? Crikey!