Riddles

[Davecom3]

Of course, the best configuration is the one that uses the least rabbits and the least rabbits per bottle.

[Zathyr]

With a cube of bottles, it would take even less. But that's 30 rabbits, and doesn't beat Game's 10. A binary search would take 11 bunnies, and more time.

Ah, but you can do it with just 2 bunnies! Here's how: you rub the two bunnies together to create static electricity. (Really a glass bottle and 1 bunny would be enough, but Bob said it wasn't 0 or 1, so..) Then it's just a simple matter of testing the conductivity of the liquid in each bottle. The liquid with a different conductivity is the poison! Plus you don't need to waste any water feeding them and you have 2 perfectly unpoisoned bunnies to eat as well.

[Davecom3]

Frankly, with the ten rabbits, you have to eliminate the possible water where all 10 rabbits drink, the 10 bottles of water where all but one rabbit drinks and 13 of the combinations where 8 rabbits drink. You might be able to find the poison with no rabbits drinking, though, as there's nothing that says the poison weighs the same as the water.

[Davecom3]

And the reason this works is that the bottles have two states, poison and water, making this a Base-2 problem. 2^1=2, 2^2=4, 2^3=8, 2^4=16, 2^5=32, 2^6=64, 2^7=128, 2^8= 256, 2^9=512, and 2^10=1,024, with 24 possibilities more than needed to figure out which bottle holds the poison if you use 10 rabbits.

[I'mBob]

To detect poison we will need 10 bunnies. First, number those bottles from 1 to 1000 and bunnies from 0 to 9. Then for each bottle convert it's number to binary and give drink from that bottle only to those bunnies, whose number corresponds to "1" bit. For example, from bottle 984=1111011000 will drink bunnies 9,8,7,6,4,3. When bunnies will die from poison, reverse coding procedure: take numbers of dead bunnies and set corresponding bits to 1 and other bits to 0. Convert into decimal to get number of poisoned bottle.

Oh, that's right. I didn't notice it.

This riddle is used when learning binary if anyone is wondering.

[gamecreator]

I see there is some activity besides me in solving math riddles here, so try this:

There is a sequence of 5 numbers: 2 9 2 9 2. You need to get 100 by placing braces and signs of arithmetic operations (+-*/^) around those numbers and processing resulting expression. All Any numbers can not be moved from their positions and must be delimited from each other by signs and/or braces.

[BadgeAddict]

is is possible to use ( ), such as ((2*9)/2)(2+9)

[Davecom3]

All numbers can't? Does that mean some numbers can?

[gamecreator]

is is possible to use ( ), such as ((2*9)/2)(2+9)

Yes, by braces i meant (). Also it is not possible for numbers to swap places.

All numbers can't? Does that mean some numbers can?

Any number can not be moved.

[BadgeAddict]

is is possible to use ( ), such as ((2*9)/2)(2+9)

Yes, by braces i meant ()

To reword this

NO, you cannot move any of the numbers.

[Davecom3]

Can you use . or ^?

[gamecreator]

Oops, I messed things up. Yes, ^ is allowed.

[Davecom3]

But adding a decimal isn't?

[gamecreator]

Adding decimal point is not allowed. Only operators and braces.

[BadgeAddict]

To help your brain move in what i hope is the right direction. Here is an idea though it comes out wrong:

2*(9+2+9)*2=80

[Davecom3]

(2/(9+2+9))^-2? This allowed?

[BadgeAddict]

technically you put two symbols between the last 9 and 2 but its not my call. I also can't read.

I have my own question, can we take the square roots of numbers?

[gamecreator]

(2/(9+2+9))^-2? This allowed?

You need to put -2 in braces, everything else is correct. Your turn.

technically you put two symbols between the last 9 and 2 but its not my call.

After reading this I thought I messed up again and somehow stated that there can be only one operator between numbers.

I have my own question, can we take the square roots of numbers?

No, also I can't even imagine how that can be helpful.

[Davecom3]

Actually, -2 really doesn't need parentheses.

[gamecreator]

Whatever. But without them it looks a bit confusing.

[Davecom3]

Pronounced differently but spelled the same
I have many meanings from obscure to mundane
In a trip across water I get there before you
In precipitation amazing, a marvel to awe you

One naming of me means to acknowledge the praise
I move fastest in music as the violin maestro plays
Taught to children of all ages , or trip up they would
I was also much favored by a notorious Hood.

[SamWiser]

A bow?

[Davecom3]

yes

[SamWiser]

Yay, I got one!

What is black when you but it, red when you use it, and grey when you throw it away?

[Davecom3]

That one is rather simple, I'm afraid. It's coal, perhaps charcoal.