Riddles and Puzzles

[Archie_tect]

I prefer the certainty of my low-tech solution.

 

[classic33]

Robotic Enigma

Three robots A, B, and C are called, in some order, True (T), False (F) and Random (R).
(T) is programmed to speaks truly, (F) falsely, but whether (R) speaks truly or falsely is a completely random matter.

The robots can answer only YES or NO. Each robot is equipped with two small lamps - red and white.
When a robot responds – the red light lights up, but you do not know he said YES or NO. When there is no answer – lights up the white light.

Your task is to determine the identities of A, B, and C by asking no more than three questions; each question must be put to exactly one robot.

 

[Over The Hill]

The reason it's a "no" (and to give us some solidarity in our misery) is, I think, because there could be 20 red hats, or 20 black hats, or any combination thereof. So the prisoner can't look at the ones in front and determine his hat colour.....I think.

If you can explain my "no" I would appreciate it !

Thanks for explaining. I was wondering where I went wrong!
I think I have it now.

 

[Over The Hill]

Prisoners On Death Row
You are one of 20 prisoners on death row with the execution date set for tomorrow.

Your king is a ruthless man who likes to toy with his people's miseries. He comes to your cell today and tells you:

“I’m gonna give you prisoners a chance to go free tomorrow. You will all stand in a row (queue) before the executioner and we will put a hat on your head, either a red or a black one. Of course you will not be able to see the color of your own hat; you will only be able to see the prisoners in front of you with their hats on; you will not be allowed to look back or communicate together in any way (talking, touching.....)

(The prisoner in the back will be able to see the 19 prisoners in front of him
The one in front of him will be able to see 18…)

Starting with the last person in the row, the one who can see everybody in front of him, he will be asked a simple question:WHAT IS THE COLOR OF YOUR HAT?

He will be only allowed to answer “BLACK” or “RED”. If he says anything else you will ALL be executed immediately.

If he guesses the right color of the hat on his head he is set free, otherwise he is put to death. And we move on to the one in front of him and ask him the same question and so on…

Well, good luck tomorrow, HA HA HA HA HA HA!”

Now since you all can communicate freely during the night, can you find a way to guarantee the freedom of some prisoners tomorrow?
How many will win their freedom?

Second attempt
Back man knows nothing so guesses 50/50
BUT he can see the colour of the man in front .
They prisoners can devise a code to call the colour of the hat in front when they call their own. So for example "Hat Black" could mean the man in front is red while "Black hat" means the one in front is black.
Each then can call their own colour as they have been informed by the one behind and also tell the one in front his colour.
First man is on 50/50 but all the rest walk free.

Just posted this and seen AC has got the same answer already.

 

[shouldbeinbed]

Second attempt
Back man knows nothing so guesses 50/50
BUT he can see the colour of the man in front .
They prisoners can devise a code to call the colour of the hat in front when they call their own. So for example "Hat Black" could mean the man in front is red while "Black hat" means the one in front is black.
Each then can call their own colour as they have been informed by the one behind and also tell the one in front his colour.
First man is on 50/50 but all the rest walk free.

Just posted this and seen AC has got the same answer already.

You've just killed them all by having them say Hat along with the colour. The rules were very strict. I like Archie's low tec solution.

 

[AndyRM]

Robotic Enigma

Three robots A, B, and C are called, in some order, True (T), False (F) and Random (R).
(T) is programmed to speaks truly, (F) falsely, but whether (R) speaks truly or falsely is a completely random matter.

The robots can answer only YES or NO. Each robot is equipped with two small lamps - red and white.
When a robot responds – the red light lights up, but you do not know he said YES or NO. When there is no answer – lights up the white light.

Your task is to determine the identities of A, B, and C by asking no more than three questions; each question must be put to exactly one robot.

Jeebus. This has been breaking my mind for a while now! I've even got Mrs RM on the case but I don't think she's taking it very seriously.

 

[Archie_tect]

Ask A if B is lying, ask B if C is lying and ask C id A is lying... no idea what the results tell you but it will certainly mess up your mind working it out.....

 

[classic33]

An whoDunnit
There has been a murder in the house, and you must find whodunnit.

You ask three questions of each of six suspects, four of whom are liars.
Liars will give at least one, but not necessarily all three, incorrect answers.
One of the six is the murderer.

The house has eight rooms: Kitchen, Living Room, Bathroom, Garage, Basement, 3 Bedrooms.
Only one person (the murderer) was present in the killing room.
Any number of people could have been in any of the other rooms at the same time.

You must identify the murderer and determine which four are liars, and who was in which room.

Here are the responses to your questions:

John: Pat was in the 2nd bedroom. So was I.
Tim was in the bathroom.

Mary: I agree with John that Tim was in the bathroom and Pat was in the 2nd bedroom.
But I think that John was in the living room, OH MY GOD!

Pat: Mary was in the kitchen with Don.
But I was in the bathroom.

Tim: I still say Pat was in the 2nd bedroom and Kelly was in the bathroom.
John was in the 1st bedroom.

Kelly: Pat was in the bathroom with Don.
And Mary was in the kitchen.

Don: Tim was in the kitchen.
And I was in the 2nd bedroom with Pat.

WhoDunnit and where were they?

 

[classic33]

Three Question Quickie
Q: Twelve. A: Six.
Q: Six. A: Three.
Q: Four. A: ?

 

[classic33]

An Odd Liar
Richard is a strange liar. He lies on six days of the week, but on the seventh day, he always tells the truth. He made the following statements on three successive days:

Day 1: "I lie on Monday and Tuesday."
Day 2: "Today, it's Thursday, Saturday, or Sunday."
Day 3: "I lie on Wednesday and Friday."

The Question: On which day does Richard tell the truth?

 

[classic33]

Answers Please
Here are three answers:

1. Answer A
2. Answer A or B
3. Answer B or C

There is only one correct answer to this question. Which answer is this?

 

[classic33]

Shunting Solution Sought
How must the locomotive shunt the wagons, to arrive in a situation where the wagons have changed places and the locomotive is back in its starting position?

 

[Rasmus]

An Odd Liar
Richard is a strange liar. He lies on six days of the week, but on the seventh day, he always tells the truth. He made the following statements on three successive days:

Day 1: "I lie on Monday and Tuesday."
Day 2: "Today, it's Thursday, Saturday, or Sunday."
Day 3: "I lie on Wednesday and Friday."

The Question: On which day does Richard tell the truth?

Tuesday.

 

[chewa]

1
11
21
1211
111221

What is the next sequence? ( I know it is easy but only one I can think of).

 

[AndyRM]

Three Question Quickie
Q: Twelve. A: Six.
Q: Six. A: Three.
Q: Four. A: ?

Is 2 too obvious? I'm probably missing something.