3 doors, three guards, one stone Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern) Announcing the arrival of Valued Associate #679: Cesar Manara Unicorn Meta Zoo #1: Why another podcast?Two doors with two guards - one lies, one tells the truthLying, truthful and merciless guards (variation)Two doors with three guards - one lies, one tells the truth, and one is unreliableWhich is the door to heavenWhy does this answer to “two doors with two guards” work?The last question to the guardsClassic 2 Guards But With 3 Doors InsteadClassic two guards and two doorsMonty's LabyrinthPossible answer to the Heaven Hell Door riddle
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3 doors, three guards, one stone
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)
Announcing the arrival of Valued Associate #679: Cesar Manara
Unicorn Meta Zoo #1: Why another podcast?Two doors with two guards - one lies, one tells the truthLying, truthful and merciless guards (variation)Two doors with three guards - one lies, one tells the truth, and one is unreliableWhich is the door to heavenWhy does this answer to “two doors with two guards” work?The last question to the guardsClassic 2 Guards But With 3 Doors InsteadClassic two guards and two doorsMonty's LabyrinthPossible answer to the Heaven Hell Door riddle
$begingroup$
You are in a room with three doors. You find out, that behind two of these doors, the darkest pit of hell is waiting for you to make a mistake. The other door, leads to heaven, where you, obviously, want to get.
Each door is guarded by a guard:
- Michael, who tells truth with 75% chance;
- Vlad, who lies with 90% chance;
- John, who lies with 70% chance.
You do not know who is who, or which door he guards. You may ask each guard 2 questions max, but no more than 4 questions in total, because those guys do not like long conversations.
The other thing you have is a magic stone, that can be used only once. This stone makes the event with the lowest chance to occur.
What is the easiest way, which gives you the most chances to go to heaven?
Hint: the solution lies on the surface.
logical-deduction probability liars
asked 4 hours ago
Andrii ChumakovAndrii Chumakov
415
New contributor
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
You are in a room with three doors. You find out, that behind two of these doors, the darkest pit of hell is waiting for you to make a mistake. The other door, leads to heaven, where you, obviously, want to get.
Each door is guarded by a guard:
- Michael, who tells truth with 75% chance;
- Vlad, who lies with 90% chance;
- John, who lies with 70% chance.
You do not know who is who, or which door he guards. You may ask each guard 2 questions max, but no more than 4 questions in total, because those guys do not like long conversations.
The other thing you have is a magic stone, that can be used only once. This stone makes the event with the lowest chance to occur.
What is the easiest way, which gives you the most chances to go to heaven?
Hint: the solution lies on the surface.
logical-deduction probability liars
asked 4 hours ago
Andrii ChumakovAndrii Chumakov
415
New contributor
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
$begingroup$
Are only yes/no questions allowed?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, you may ask them whatever question you want, but there is no guard, who always tells the truth, which makes it difficult to find the correct door using qs like "What's 1 + 1"
$endgroup$
– Andrii Chumakov
2 hours ago
$begingroup$
So, if you ask Michael "Who are you?" without using the stone and he decides to lie (or you use the stone, so he'll lie) could he say either "Vlad" or "John"?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, yes, that's what would happen in this case
$endgroup$
– Andrii Chumakov
2 hours ago
add a comment |
$begingroup$
You are in a room with three doors. You find out, that behind two of these doors, the darkest pit of hell is waiting for you to make a mistake. The other door, leads to heaven, where you, obviously, want to get.
Each door is guarded by a guard:
- Michael, who tells truth with 75% chance;
- Vlad, who lies with 90% chance;
- John, who lies with 70% chance.
You do not know who is who, or which door he guards. You may ask each guard 2 questions max, but no more than 4 questions in total, because those guys do not like long conversations.
The other thing you have is a magic stone, that can be used only once. This stone makes the event with the lowest chance to occur.
What is the easiest way, which gives you the most chances to go to heaven?
Hint: the solution lies on the surface.
logical-deduction probability liars
asked 4 hours ago
Andrii ChumakovAndrii Chumakov
415
New contributor
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
You are in a room with three doors. You find out, that behind two of these doors, the darkest pit of hell is waiting for you to make a mistake. The other door, leads to heaven, where you, obviously, want to get.
Each door is guarded by a guard:
- Michael, who tells truth with 75% chance;
- Vlad, who lies with 90% chance;
- John, who lies with 70% chance.
You do not know who is who, or which door he guards. You may ask each guard 2 questions max, but no more than 4 questions in total, because those guys do not like long conversations.
The other thing you have is a magic stone, that can be used only once. This stone makes the event with the lowest chance to occur.
What is the easiest way, which gives you the most chances to go to heaven?
Hint: the solution lies on the surface.
logical-deduction probability liars
logical-deduction probability liars
asked 4 hours ago
Andrii ChumakovAndrii Chumakov
415
New contributor
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 4 hours ago
Andrii ChumakovAndrii Chumakov
415
New contributor
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 2 hours ago
Andrii Chumakov
asked 4 hours ago
Andrii ChumakovAndrii Chumakov
415
New contributor
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 4 hours ago
Andrii ChumakovAndrii Chumakov
415
asked 4 hours ago
Andrii ChumakovAndrii Chumakov
415
415
New contributor
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Andrii Chumakov is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$begingroup$
Are only yes/no questions allowed?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, you may ask them whatever question you want, but there is no guard, who always tells the truth, which makes it difficult to find the correct door using qs like "What's 1 + 1"
$endgroup$
– Andrii Chumakov
2 hours ago
$begingroup$
So, if you ask Michael "Who are you?" without using the stone and he decides to lie (or you use the stone, so he'll lie) could he say either "Vlad" or "John"?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, yes, that's what would happen in this case
$endgroup$
– Andrii Chumakov
2 hours ago
add a comment |
$begingroup$
Are only yes/no questions allowed?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, you may ask them whatever question you want, but there is no guard, who always tells the truth, which makes it difficult to find the correct door using qs like "What's 1 + 1"
$endgroup$
– Andrii Chumakov
2 hours ago
$begingroup$
So, if you ask Michael "Who are you?" without using the stone and he decides to lie (or you use the stone, so he'll lie) could he say either "Vlad" or "John"?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, yes, that's what would happen in this case
$endgroup$
– Andrii Chumakov
2 hours ago
$begingroup$
Are only yes/no questions allowed?
$endgroup$
– EKons
2 hours ago
$begingroup$
Are only yes/no questions allowed?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, you may ask them whatever question you want, but there is no guard, who always tells the truth, which makes it difficult to find the correct door using qs like "What's 1 + 1"
$endgroup$
– Andrii Chumakov
2 hours ago
$begingroup$
@EKons, you may ask them whatever question you want, but there is no guard, who always tells the truth, which makes it difficult to find the correct door using qs like "What's 1 + 1"
$endgroup$
– Andrii Chumakov
2 hours ago
$begingroup$
So, if you ask Michael "Who are you?" without using the stone and he decides to lie (or you use the stone, so he'll lie) could he say either "Vlad" or "John"?
$endgroup$
– EKons
2 hours ago
$begingroup$
So, if you ask Michael "Who are you?" without using the stone and he decides to lie (or you use the stone, so he'll lie) could he say either "Vlad" or "John"?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, yes, that's what would happen in this case
$endgroup$
– Andrii Chumakov
2 hours ago
$begingroup$
@EKons, yes, that's what would happen in this case
$endgroup$
– Andrii Chumakov
2 hours ago
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
No questions are required!
Use the magic stone, then try one of the doors. It's less likely to get the right door (1/3) than one of the wrong ones (2/3), so you'll end up in the right place
answered 1 hour ago
StephenTGStephenTG
1,4621921
$endgroup$
add a comment |
$begingroup$
I'd go with this:
Go to any guard, use the magic stone, and ask the question:
Which of the remaining two guards will lie?
If it is Michel
Since he will lie, so he'll say
"None"
If it is Vlad
He will point to one guard, who will be John, so the other would be Michel
If it is John
He will point to one guard, who will be Vlad, so the other would be Michel
So
I'll identify Michel who will say the truth 75% of times, and ask him the second question
"Which door leads to heaven"
It is a 75% chance that he'll tell the truth
This isn't an optimal solution, so work is still in progress
answered 1 hour ago
AkariAkari
647223
$endgroup$
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
No questions are required!
Use the magic stone, then try one of the doors. It's less likely to get the right door (1/3) than one of the wrong ones (2/3), so you'll end up in the right place
answered 1 hour ago
StephenTGStephenTG
1,4621921
$endgroup$
add a comment |
$begingroup$
No questions are required!
Use the magic stone, then try one of the doors. It's less likely to get the right door (1/3) than one of the wrong ones (2/3), so you'll end up in the right place
answered 1 hour ago
StephenTGStephenTG
1,4621921
$endgroup$
add a comment |
$begingroup$
No questions are required!
Use the magic stone, then try one of the doors. It's less likely to get the right door (1/3) than one of the wrong ones (2/3), so you'll end up in the right place
answered 1 hour ago
StephenTGStephenTG
1,4621921
$endgroup$
No questions are required!
Use the magic stone, then try one of the doors. It's less likely to get the right door (1/3) than one of the wrong ones (2/3), so you'll end up in the right place
answered 1 hour ago
StephenTGStephenTG
1,4621921
answered 1 hour ago
StephenTGStephenTG
1,4621921
answered 1 hour ago
StephenTGStephenTG
1,4621921
answered 1 hour ago
StephenTGStephenTG
1,4621921
1,4621921
add a comment |
add a comment |
$begingroup$
I'd go with this:
Go to any guard, use the magic stone, and ask the question:
Which of the remaining two guards will lie?
If it is Michel
Since he will lie, so he'll say
"None"
If it is Vlad
He will point to one guard, who will be John, so the other would be Michel
If it is John
He will point to one guard, who will be Vlad, so the other would be Michel
So
I'll identify Michel who will say the truth 75% of times, and ask him the second question
"Which door leads to heaven"
It is a 75% chance that he'll tell the truth
This isn't an optimal solution, so work is still in progress
answered 1 hour ago
AkariAkari
647223
$endgroup$
add a comment |
$begingroup$
I'd go with this:
Go to any guard, use the magic stone, and ask the question:
Which of the remaining two guards will lie?
If it is Michel
Since he will lie, so he'll say
"None"
If it is Vlad
He will point to one guard, who will be John, so the other would be Michel
If it is John
He will point to one guard, who will be Vlad, so the other would be Michel
So
I'll identify Michel who will say the truth 75% of times, and ask him the second question
"Which door leads to heaven"
It is a 75% chance that he'll tell the truth
This isn't an optimal solution, so work is still in progress
answered 1 hour ago
AkariAkari
647223
$endgroup$
add a comment |
$begingroup$
I'd go with this:
Go to any guard, use the magic stone, and ask the question:
Which of the remaining two guards will lie?
If it is Michel
Since he will lie, so he'll say
"None"
If it is Vlad
He will point to one guard, who will be John, so the other would be Michel
If it is John
He will point to one guard, who will be Vlad, so the other would be Michel
So
I'll identify Michel who will say the truth 75% of times, and ask him the second question
"Which door leads to heaven"
It is a 75% chance that he'll tell the truth
This isn't an optimal solution, so work is still in progress
answered 1 hour ago
AkariAkari
647223
$endgroup$
I'd go with this:
Go to any guard, use the magic stone, and ask the question:
Which of the remaining two guards will lie?
If it is Michel
Since he will lie, so he'll say
"None"
If it is Vlad
He will point to one guard, who will be John, so the other would be Michel
If it is John
He will point to one guard, who will be Vlad, so the other would be Michel
So
I'll identify Michel who will say the truth 75% of times, and ask him the second question
"Which door leads to heaven"
It is a 75% chance that he'll tell the truth
This isn't an optimal solution, so work is still in progress
answered 1 hour ago
AkariAkari
647223
answered 1 hour ago
AkariAkari
647223
answered 1 hour ago
AkariAkari
647223
answered 1 hour ago
AkariAkari
647223
647223
add a comment |
add a comment |
Andrii Chumakov is a new contributor. Be nice, and check out our Code of Conduct.
Andrii Chumakov is a new contributor. Be nice, and check out our Code of Conduct.
Andrii Chumakov is a new contributor. Be nice, and check out our Code of Conduct.
Andrii Chumakov is a new contributor. Be nice, and check out our Code of Conduct.
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$begingroup$
Are only yes/no questions allowed?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, you may ask them whatever question you want, but there is no guard, who always tells the truth, which makes it difficult to find the correct door using qs like "What's 1 + 1"
$endgroup$
– Andrii Chumakov
2 hours ago
$begingroup$
So, if you ask Michael "Who are you?" without using the stone and he decides to lie (or you use the stone, so he'll lie) could he say either "Vlad" or "John"?
$endgroup$
– EKons
2 hours ago
$begingroup$
@EKons, yes, that's what would happen in this case
$endgroup$
– Andrii Chumakov
2 hours ago