It wouldn't be inaccurate to assume that I couldn't exactly not say

Logic Level 3

You met 3 people:

Person A who speaks the truth.
Person B who always lies.
Person C who sometimes tells the truth and sometimes lies.

What is the minimum number of questions you need to ask to deduce who always speaks the truth, who always lies, and who sometimes tells the truth and sometimes lies?

I've seen this many times, so I decided to post it.

1 2 5 4 3

1 solution

Taylor Shobe
Jun 28, 2015

"3", but possibly only "2" if we allow for half-truths or partial-truths. In other words, if we consider the following statement to contain some truth and some lying (mixture), and NOT just consider the entire sentence to be a lie because it contains at least one lie.

"1+1=2, and 1+2=5"

To me, someone who NEVER told the truth and ALWAYS lied would never even admit that 1+1=2 in the sentence above, because that part is at least true.

If we allow that, then the answer should actually be "2".

So, it depends on how we define "always lies", which this problem does not do in this regard.

Simply in two steps:

Ask one person: "If I asked if you are C, would you say 'yes'?" If the answer is yes, then you are talking to C. Then just move on to another person and ask a question you know the answer to. You can then identify A, B, and C.

Feathery Studio - 5 years, 11 months ago

But not sufficient. They could say 'no', and then you would have learned nothing. In fact, it may be impossible for C to answer that question at all.

Thomas Weber - 5 years, 11 months ago

cant i ask "am i a human?"

Akash singh - 5 years, 9 months ago

You can use Phyton for answer !!

Syed Baqir - 5 years, 9 months ago

@Syed Baqir – what is python?

i dont know about it

Akash singh - 5 years, 9 months ago

@Akash Singh – I mean Python , sorry .

It is programming language.

Syed Baqir - 5 years, 9 months ago

the problem has alot of ambiguity it shall declare whether the 3 know each other or no if so 2 is the right answer because at first you will ask all of them any simple known question like is "sky is blue?" or "does "1+1=2" then the one who always lie will say lie then for example let lie teller is person B and ask him if does person A is the truth teller? if he answered yes then it's person C is the truth teller and person A is the lair or truth teller and vice versa

Mahmod Abass - 5 years, 10 months ago

It should not be max Qs i.e. 5 in order to investigate ?

Syed Baqir - 5 years, 11 months ago

Huh?? What are you asking?

Taylor Shobe - 5 years, 11 months ago

I mean the more question is asked , Reliable conclusion would be obtained. I mean the larger the sample size is the survey is more likely to be valid

Syed Baqir - 5 years, 11 months ago

@Syed Baqir – Really this problem confused me

Manvendra Singh - 5 years, 7 months ago

It wouldn't be inaccurate to assume that I couldn't exactly not say

I've seen this many times, so I decided to post it.

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