Slander wrote:

Poisoned bottle riddle:

You have a wine cellar that contains 1000 bottles of wine.  Unfortunately, your evil rival sneaked in and poisoned some of the bottles (stuck a needle in the cork with poison, let's say).  You have no idea which ones or even how many were poisoned.  But you LOVE your wine, and can't spare to throw all 1000 bottles out.  You just happen to be a researcher and have at your disposal 10 lab rats and you plan to feed them each some wine, in some way, to discover which bottles are poisoned bottles (you feel bad about killing the rats, but DAMN you love your wine).

What do you do to determine ALL of the poisoned bottles?

You know, I totally screwed this one up (my memory must not be as good as once it was) - my apologies.  I realized it as I was trying to re-solve this to make sure I had the answer right - and realized I messed up the question.  Let's try this again...

Poisoned bottle riddle, take 2:

You have a wine cellar that contains 1000 bottles of wine.  Unfortunately, your evil rival sneaked in and poisoned a SINGLE bottle (stuck a needle in the cork with poison, let's say).  You have no idea which one. The poison is deadly and only a couple drops of poisoned wine will kill you - but it will take a few hours to kick in and kill you (you won't know until a couple hours after drinking that you drank poisoned wine).

But you LOVE your wine, and need to get your drink on TONIGHT!  You just happen to be a researcher and have at your disposal 10 lab rats.  You could feed some wine to them 10 at a time, but that would take days and days and you simply do not have the time to wait - you need your wine tonight!  (of course you feel bad about killing the rats, but DAMN you love your wine).

Also, these are special lab rats that can consume a staggering amount of wine.  The wine will not kill them, only drinking poisoned wine will.

What do you do to locate the poisoned bottle as quickly as possible?

(There - that should be much easier.  Again, sorry for the screw up)

weathertop wrote:

Slander wrote:

Poisoned bottle riddle:

You have a wine cellar that contains 1000 bottles of wine.  Unfortunately, your evil rival sneaked in and poisoned some of the bottles (stuck a needle in the cork with poison, let's say).  You have no idea which ones or even how many were poisoned.  But you LOVE your wine, and can't spare to throw all 1000 bottles out.  You just happen to be a researcher and have at your disposal 10 lab rats and you plan to feed them each some wine, in some way, to discover which bottles are poisoned bottles (you feel bad about killing the rats, but DAMN you love your wine).

What do you do to determine ALL of the poisoned bottles?

let them breed. and pace yourself on the drinking.

+1  =D

Slander wrote:

weathertop wrote:

let them breed. and pace yourself on the drinking.

ahahahah.  The original version of this riddle (or at least the one I heard) was that you had 10 servants working for you because you were rich enough to have 1000 bottles of wine that you cared that much about.  And you'd poison your servants to figure it out.  So at least I toned it down a little by going to rats

Does someone work for Microsoft? =D

itsnotatumor wrote:

Slander wrote:

weathertop wrote:

let them breed. and pace yourself on the drinking.

ahahahah.  The original version of this riddle (or at least the one I heard) was that you had 10 servants working for you because you were rich enough to have 1000 bottles of wine that you cared that much about.  And you'd poison your servants to figure it out.  So at least I toned it down a little by going to rats

Does someone work for Microsoft? =D

No.  But I did interview there a few times way back when I was in college - about 18 years ago - DAMN, I'm getting old!

I don't think I got my earlier ones from there, but I do remember some that they did give me.  If I can remember them (properly this time), I'll post them.

Slander wrote:

Slander wrote:

Poisoned bottle riddle:

You have a wine cellar that contains 1000 bottles of wine.  Unfortunately, your evil rival sneaked in and poisoned some of the bottles (stuck a needle in the cork with poison, let's say).  You have no idea which ones or even how many were poisoned.  But you LOVE your wine, and can't spare to throw all 1000 bottles out.  You just happen to be a researcher and have at your disposal 10 lab rats and you plan to feed them each some wine, in some way, to discover which bottles are poisoned bottles (you feel bad about killing the rats, but DAMN you love your wine).

What do you do to determine ALL of the poisoned bottles?

You know, I totally screwed this one up (my memory must not be as good as once it was) - my apologies.  I realized it as I was trying to re-solve this to make sure I had the answer right - and realized I messed up the question.  Let's try this again...

 

Poisoned bottle riddle, take 2:

You have a wine cellar that contains 1000 bottles of wine.  Unfortunately, your evil rival sneaked in and poisoned a SINGLE bottle (stuck a needle in the cork with poison, let's say).  You have no idea which one. The poison is deadly and only a couple drops of poisoned wine will kill you - but it will take a few hours to kick in and kill you (you won't know until a couple hours after drinking that you drank poisoned wine).

But you LOVE your wine, and need to get your drink on TONIGHT!  You just happen to be a researcher and have at your disposal 10 lab rats.  You could feed some wine to them 10 at a time, but that would take days and days and you simply do not have the time to wait - you need your wine tonight!  (of course you feel bad about killing the rats, but DAMN you love your wine).

Also, these are special lab rats that can consume a staggering amount of wine.  The wine will not kill them, only drinking poisoned wine will.

What do you do to locate the poisoned bottle as quickly as possible?

 

(There - that should be much easier.  Again, sorry for the screw up)

Looks much easier now indeed ;)

I would divide the 1000 bottles in 10*90 + 100.

I would give each rat 90 drops from 90 different bottles and keep 100 bottles apart. 

-- If no rat dies, I am left with 100 bottles and 10 rats. I'll give 10 drops from 10 different bottles each. I am left with 10 bottles and 9 rats. 1 drop each and I know which is the poisoned bottle, whether 1 rat will die or none.

-- If 1 rat dies, I am left with 90 bottles and 9 rats. I'll give 9 drops from 9 different bottles each. I am left with 9 bottles and 8 rats (or even 9 rats). 1 drop each and I know which is the poisoned bottle, whether 1 rat will die or not.

So it will have taken 3 tasting sessions.

Toto wrote:

...

So it will have taken 3 tasting sessions.

Not bad.  But it can be done in fewer tasting sessions. Think one.

Here's an easy one I got from Microsoft when I was interviewing for an internship way back in the day.

Gold Bar riddle:

The only mechanic you trust with your car is this eccentric guy that only accepts being paid daily in gold.  He needs to work on your car for seven days and you agree that the entire job is worth a gold bar - but he insists to be paid daily for what he is owed. You have a gold bar that just happens to be marked into seven equal pieces.  However, you are only allowed to make two cuts in the bar.  Since you must settle at the end of the day, how do you do it?

And here's an old favorite of mine:

There's an island divided into two distinct sides by a shared lagoon.  One side is called HE, and the other is called HA.  Everyone from HE lies and everyone from HA tells the truth.

You arrive at the lagoon to find a bunch of kids from both sides of the island playing together.  Three come up to say hi and you greet them, having no idea which side of the island they are from.  You ask the first kid, "Which side of the island are you from?"  He replies, but the kids playing in the background make a loud noise and you're unable to hear his reply.  You then ask the second kid, "I didn't hear that. Could you tell me what he (the first kid) said?".  The second kid replies, "Oh, he said he was from HA."  Thinking about that - you're not sure, so you ask the third kid, "I didn't hear what the first kid said, where did he say he was from?"  The third kid replies "Oh, he said he was from HE."

Which side is the third kid from?

Slander wrote:

And here's an old favorite of mine:

There's an island divided into two distinct sides by a shared lagoon.  One side is called HE, and the other is called HA.  Everyone from HE lies and everyone from HA tells the truth.

You arrive at the lagoon to find a bunch of kids from both sides of the island playing together.  Three come up to say hi and you greet them, having no idea which side of the island they are from.  You ask the first kid, "Which side of the island are you from?"  He replies, but the kids playing in the background make a loud noise and you're unable to hear his reply.  You then ask the second kid, "I didn't hear that. Could you tell me what he (the first kid) said?".  The second kid replies, "Oh, he said he was from HA."  Thinking about that - you're not sure, so you ask the third kid, "I didn't hear what the first kid said, where did he say he was from?"  The third kid replies "Oh, he said he was from HE."

Which side is the third kid from?

The third kid is from HE.

All the kids from HE lie, so they would say they are from HA

All the kids from HA tell the truth, so they would say they are from HA

So no kid would ever say he was from HE which means the third kid lied.

gold bar, split into 1,2,4..

pay:

1. 1
2. 2
3. 1+2
4. 4
5. 4+1
6. 4+2
7. 4+2+1

Rat/wine/poison.

Number wine bottles in binary from 1 - 1000:

0000000001

0000000010

0000000011

0000000100

[...]

1111101000

Mix up some wine for each rat.  Rat #1 gets wine from every bottle that has a 1 in the 1st position, rat #2 gets wine from every bottle that has a 1 in 2nd position, etc.

Make a new number, put a zero if the rat for that position lived, and a 1 if the rat from that position died.   That is the binary ID of the poisonous bottle.

Slander wrote:

itsnotatumor wrote:

Slander wrote:

weathertop wrote:

let them breed. and pace yourself on the drinking.

ahahahah.  The original version of this riddle (or at least the one I heard) was that you had 10 servants working for you because you were rich enough to have 1000 bottles of wine that you cared that much about.  And you'd poison your servants to figure it out.  So at least I toned it down a little by going to rats

Does someone work for Microsoft? =D

No.  But I did interview there a few times way back when I was in college - about 18 years ago - DAMN, I'm getting old!

I don't think I got my earlier ones from there, but I do remember some that they did give me.  If I can remember them (properly this time), I'll post them.

Lol, I was mainly referring to beta testing the servants.  =P

Slander wrote:

(There - that should be much easier.  Again, sorry for the screw up)

Thanks, that's what I needed, so then binary works (Ozy and I had the same answer).

I've been battling this riddle for the last 2 days, trying to figure out how to handle the multiple bottles killing lots of my rats, but now that you say it's just one bottle, it's much easier.
I was trying to do some sort of search algorithm counting backwards in binary, and was running out of rats quickly.

Here's a different solution to a famous riddle:
(sent to me by a friend at work after I spent lunch with them letting them work through the 12 billiard balls problem)

http://xkcd.com/1134/

Ozyman wrote:

gold bar, split into 1,2,4..

pay:

1. 1
2. 2
3. 1+2
4. 4
5. 4+1
6. 4+2
7. 4+2+1

Correct, if you mean:

1. Give 1

2. Take back 1, give 2

3. Give 2

4. Take back 1 and 2, give 4

5. Give 1

6. Take 1, give 2

7. Give 1

Ozyman wrote:

Rat/wine/poison.

Number wine bottles in binary from 1 - 1000:

...

Make a new number, put a zero if the rat for that position lived, and a 1 if the rat from that position died.   That is the binary ID of the poisonous bottle.

 

Yep.

BorisTheFrugal wrote:

Here's a different solution to a famous riddle:
(sent to me by a friend at work after I spent lunch with them letting them work through the 12 billiard balls problem)

http://xkcd.com/1134/

 

Ahahah  - Leave the Wolf!

I think I have one that's a slightly more difficult version of that:

Crossing the Bridge riddle:

Four people come to an old, shaky, unstable bridge in the middle of the night.  They realize that at most two of them can be on the bridge at any given time, else it will collapse.  They have a single flashlight and in order to cross the bridge, you have to have the flashlight to see your way past missing planks in the bridge.  Each of the four people travel at different speeds.  Person A can make a single crossing in 1 min, B can cross in 2 min, C can cross in 5 min, and D can cross in 10 min.  When two people cross together, they cross at the speed of the slowest person to be able to both use the single flashlight.

In what order do you send them to get them all over the quickest?

Slander wrote:

Four people come to an old, shaky, unstable bridge in the middle of the night.  They realize that at most two of them can be on the bridge at any given time, else it will collapse.  They have a single flashlight and in order to cross the bridge, you have to have the flashlight to see your way past missing planks in the bridge.  Each of the four people travel at different speeds.  Person A can make a single crossing in 1 min, B can cross in 2 min, C can cross in 5 min, and D can cross in 10 min.  When two people cross together, they cross at the speed of the slowest person to be able to both use the single flashlight.

In what order do you send them to get them all over the quickest?

is there something hard about this or am i just seein things? 19mins as far as i can see...(10,5,2 with 1 being the go between).

-> AB

A <-

-> AC

A <-

-> AD, etc

Actually, it doesn't matter the order of who A travels with, as long as A is always accompanying the person crossing.

I must be missing something..

weathertop wrote:

is there something hard about this or am i just seein things? 19mins as far as i can see...(10,5,2 with 1 being the go between).

It's a duel optimization problem.  You can do it faster than 19 min.

Try not to brute force it - that would be cheating :)