What's your favorite Riddle

[el_blubo]

What is your favorite, best, or hardest riddle you know? Post it here and see if someone can solve it. No Cheating!!!

 

I never was, yet always will be. I am never seen, yet always come. I carry nothing, yet hold much for some.

 

[~Xandria]

Nice thread idea! To be completely honest, I've never been all that great at riddles. :P Haha. That being said, I did google the answer because I was curious, lol... but I won't spoil it of course.

[Koralis]

The first thing that comes to mind is 'tomorrow' - I really want to try and not cheat to see if that's the answer or not :P so I'll check back in later to see if that's right or wrong!

[siniri]

My guess was also

"tomorrow" or "the future"

 

 

Here's one that I was very proud to solve:

 

You're captured by a weird group of people for trespassing on their land. They've got a dilemma, and they'll let you go if you solve it for them; otherwise, you'll be their captor for who knows how long. They received 12 coins identical in appearance, except that one of the coins is either heavier or lighter than the others (but they don't know which). Along with the coins, they received a simple balance, but it can only be used exactly three times before it breaks. You must figure out a foolproof way to determine which coin is different from the others in only three weighings.

[el_blubo]

Both of you got mine right

 

Dont know how to do that spoiler thing you did so I'll just put my answer in white text

 

Put half of the coins on one side and the others on the other side, see which side is lighter/heavier and divide by 2 two more times?

[siniri]

There are two ways:

1) Click on the third icon from the left on the top row (the one directly to the left of the font box), then choose "spoiler" from the dropdown box.

2) Type "[ spoiler ]" before the spoiler text (remove the spaces and quotation marks so the code will work), then "[ /spoiler ]" (again, remove spaces and quotation marks) directly after the spoiler text.

 

Your solution is not correct because you don't know if the coin that's different is lighter or heavier -- you just know it's different somehow.

[coltom]

My favorite riddle is what is the difference between a boxer and a young lady?

 

It is a terrible and inappropriate answer.

[siniri]

My favorite riddle is what is the difference between a boxer and a young lady?

 

It is a terrible and inappropriate answer.

 

One boxes in a ring, while the other has rings in a box?

 

I'm assuming that's not the answer you were going for since it wasn't that inappropriate.

[Wildbreeze]

My guess was also

"tomorrow" or "the future"

 

 

Here's one that I was very proud to solve:

 

You're captured by a weird group of people for trespassing on their land. They've got a dilemma, and they'll let you go if you solve it for them; otherwise, you'll be their captor for who knows how long. They received 12 coins identical in appearance, except that one of the coins is either heavier or lighter than the others (but they don't know which). Along with the coins, they received a simple balance, but it can only be used exactly three times before it breaks. You must figure out a foolproof way to determine which coin is different from the others in only three weighings.

Put 6 coins on each side of the balance. One side will be heavier. Remove the lighter side. Put 3 coins from the heavier set on each side, again remove the lighter side. Pick 2 of the remaining 3 coins at random and weigh them again. If one coin is heavier, there you go. If they are equal, the last coin is heavier.

(Things I learned as a child from "Cyberchase".)

[siniri]

Put 6 coins on each side of the balance. One side will be heavier. Remove the lighter side. Put 3 coins from the heavier set on each side, again remove the lighter side. Pick 2 of the remaining 3 coins at random and weigh them again. If one coin is heavier, there you go. If they are equal, the last coin is heavier.

(Things I learned as a child from "Cyberchase".)

Incorrect. You don't know if the coin in question is heavier or lighter; you just know it's different. If the coin is lighter, you'll run out of scale usage.

[Wildbreeze]

Incorrect. You don't know if the coin in question is heavier or lighter; you just know it's different. If the coin is lighter, you'll run out of scale usage.

Sorry, reread the puzzle. You don't know if it's heavier or lighter. That would work, if you knew that it was one or the other.

[siniri]

Yep, but then it would be an easy puzzle, not a hard puzzle!

 

Here's a hint to get you started; it tells you what the first weighing must be, but that's it.

 

Divide the coins in 3 groups of 4; weigh one set of 4 against another set of 4.

 

[el_blubo]

 

(well if they're even you know that the third group has the odd coin and if they're not the only thing I could think of would be to split the pile that you think is different, weigh two of those against two that you know are the same and once you find if it's one of the two coins in that group or the other, you take one of the coins from that group and then weigh it against one that that again you know is the correct weight for your third balance and if it's the same weight, it's the other coin of the two, and if it isn't that's the coin)

 

 

I really think I've got it!

[siniri]

You're on the right track.

 

Line the coins up in a row; to keep track of which is which, we'll label them 1 to 12, left to right.

1) Balance 1 through 4 vs. 5 through 8. There are 3 possible outcomes:

• 1) 1 through 4 are heavier.
• 2) 1 through 4 are lighter.
• 3) 1 through 4 weigh exactly the same as 5 through 8.

Here's the solution for the third outcome; I'll let someone else work out the second and third weighings for the first two scenarios, which are a bit trickier:

 

Since 1 through 8 all weigh the same, you know that the counterfeit coin is one of 9, 10, 11, or 12. You still don't know if it's heavier or lighter than the rest, but you can try to find out!

2) Balance 9 and 10 vs. 1 and 2 (really, you can balance it against any 2 of the 8 you know are normal). Again, there are 3 possible outcomes:

• 1) 9 and 10 are heavier than 1 and 2. Now you know that the counterfeit is heavier, and that it's either 9 or 10. For your third weighing, you can weigh either 9 or 10 against any normal coin (1-8, 11-12); if it's heavier, then the one you weighed is the counterfeit, but if it's not, then the one you didn't weigh is the counterfeit. Alternatively, you could weigh 9 vs. 10, and the heavier one would be the counterfeit.
• 2) 9 and 10 are lighter than 1 and 2. Now you know that the counterfeit is lighter, and that it's either 9 or 10. The solution is very similar to that of outcome 1: For your third weighing, you can weigh either 9 or 10 against any normal coin (1-8, 11-12); if it's lighter, then the one you weighed is the counterfeit, but if it's not, then the one you didn't weigh is the counterfeit. Alternatively, you could weigh 9 vs. 10, and the lighter one would be the counterfeit.
• 3) 9 and 10 weigh exactly the same as 1 and 2. Now you know that the counterfeit is 11 or 12, but you don't know if it's heavier or lighter! Oh no! Fortunately, you aren't required to confirm whether the counterfeit is heavier or lighter, just to identify it. For the third weighing, weigh 11 or 12 vs. any of the normal coins (1-10). If the scale is imbalanced, you know that the one you weighed is the counterfeit (and you'll be able to confirm whether it is heavier or lighter). If the scale is balanced, you'll know that the counterfeit is the one you did not weigh, but you won't know if it's heavier or lighter.

 

 

In the first two outcomes, you've only narrowed down the counterfeit to one of 1-8, so it's a bit trickier to identify which one in only 2 additional weighings, but I promise it can be done. I'll leave it to someone else to figure it out, then post the solution if no one else does by tomorrow. (I have to re-figure it out myself, but it's easier the second time around.)