Riddle

I didn’t get it. bah.

[quote=“Futility Closet”]You have nine coins and a balance scale. One of the coins is lighter than the others. Is it possible to identify it in only two weighings?

solution:

[spoiler]Number the coins 1-9. Begin by weighing 1, 2, and 3 against 4, 5, and 6. If they don’t balance, then the counterfeit coin is in the lighter group. If they do balance, then it’s among the three unweighed coins.

Having narrowed the field to three suspect coins, you can apply the same principle in the second weighing. Put one coin in each tray; if they don’t balance, the lighter coin is counterfeit, and if they do, the third suspect must be light.

J.E. Littlewood observes that a similar puzzle wasted 10,000 scientist-hours of work during World War II. “There was a proposal to drop it over Germany.”[/spoiler][/quote]

EDIT *Deleted since the answer can be found above :aiyo:

Jaboney:

Let’s say you’ve already determined 1-6 are real because 1,2,3 are equal to 4,5,6. You know this because the three 1-3 balance the three 4-6.
So the suspect coin is in 7, 8, 9.

You put two coins against eachother, say 7 and 8 to see if they are equal. Say they indeed balance. Now you’ve determined 1-8 are equal and thus 9 must be counterfeit.

Had 7 and 8 been not equal (unbalanced), then the coin that drops the lowest is heavier and thus the other coin is lighter which means it is counterfeit.

[quote=“Lili”]Jaboney:

Let’s say you’ve already determined 1-6 are real because 1,2,3 are equal to 4,5,6. You know this because the three 1-3 balance the three 4-6.
So the suspect coin is in 7, 8, 9.

You put two coins against eachother, say 7 and 8 to see if they are equal. Say they indeed balance. Now you’ve determined 1-8 are equal and thus 9 must be counterfeit.

Had 7 and 8 been not equal (unbalanced), then the coin that drops the lowest is heavier and thus the other coin is lighter which means it is counterfeit.[/quote]
Try clicking on the red word “show” in the OP :laughing:
I missed that one too until after I posted pretty much the same post you just did. :blush:

Oh, no no.
I thought Jaboney meant “I didn’t get it” like, didn’t understand the solution lol

No, I just didn’t figure out the answer on my own. (Got stuck in a binary approach.)
The solution made sense was I read it.

Then here’s a new (non mathematical) riddle for you:

What is easier to pack than to unpack?

[quote=“Dairyllama”]Then here’s a new (non mathematical) riddle for you:

What is easier to pack than to unpack?[/quote]
A rat up a drainpipe. Next?

Actually I had never considered that option. I guess because rats can fit into such small openings and squeeze through tiny gaps I never pictured them getting stuck. In fact I don’t think they get stuck. I believe it’s a scientific anomaly that prevents such things ever happening.

[quote=“Dairyllama”]Then here’s a new (non mathematical) riddle for you:

What is easier to pack than to unpack?[/quote]
I can easily pack ‘up’ and go. Don’t know about unpacking up.

[quote=“Jaboney”][quote=“Dairyllama”]Then here’s a new (non mathematical) riddle for you:

What is easier to pack than to unpack?[/quote]
I can easily pack ‘up’ and go. Don’t know about unpacking up.[/quote]

Now that is some creative thinking. My answer was actually a baby (or at least a womb), but your answer also works.

It’s the same sort of linguistic trick as:
What’s faster, hot or cold?

Trying to think of another.

[quote=“Dairyllama”][quote=“Jaboney”][quote=“Dairyllama”]Then here’s a new (non mathematical) riddle for you:

What is easier to pack than to unpack?[/quote]
I can easily pack ‘up’ and go. Don’t know about unpacking up.[/quote]

Now that is some creative thinking. My answer was actually a baby (or at least a womb), but your answer also works.[/quote]
Who on EARTH has ever tried putting a baby BACK in there? :noway:

I know some kids who ought to have been returned post haste. :wink:

[quote=“sandman”][quote=“Dairyllama”][quote=“Jaboney”][quote=“Dairyllama”]Then here’s a new (non mathematical) riddle for you:

What is easier to pack than to unpack?[/quote]
I can easily pack ‘up’ and go. Don’t know about unpacking up.[/quote]

Now that is some creative thinking. My answer was actually a baby (or at least a womb), but your answer also works.[/quote]
Who on EARTH has ever tried putting a baby BACK in there? :noway:[/quote]

Good god, no. I mean it’s easier to get the baby in their in the first place (sex) than to remove it (childbirth).

[quote=“Dairyllama”][quote=“sandman”][quote=“Dairyllama”][quote=“Jaboney”][quote=“Dairyllama”]Then here’s a new (non mathematical) riddle for you:

What is easier to pack than to unpack?[/quote]
I can easily pack ‘up’ and go. Don’t know about unpacking up.[/quote]

Now that is some creative thinking. My answer was actually a baby (or at least a womb), but your answer also works.[/quote]
Who on EARTH has ever tried putting a baby BACK in there? :noway:[/quote]

Good god, no. I mean it’s easier to get the baby in their in the first place (sex) than to remove it (childbirth).[/quote]
Um. Yes. We know. :wink:

[quote=“sandman”][quote=“Dairyllama”][quote=“Jaboney”][quote=“Dairyllama”]Then here’s a new (non mathematical) riddle for you:

What is easier to pack than to unpack?[/quote]
I can easily pack ‘up’ and go. Don’t know about unpacking up.[/quote]

Now that is some creative thinking. My answer was actually a baby (or at least a womb), but your answer also works.[/quote]
Who on EARTH has ever tried putting a baby BACK in there? :noway:[/quote]

I tell you, the things I’ve seen in “specialist” Japanese magazines…

What is this?

OK, no one is interested. It’s a ‘wind farm’.:astonished::roll_eyes:

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