### Brain Teasers

# Truths and Lies

There are three persons in a room.

One of them always tells the truth, but the others are "alternate liars": they tell the truth then lie, then truth, etc, but you do not know if they will start by telling the truth or a lie...

You can ask three questions that MUST be answered by Yes or No.

Find the truth teller.

One of them always tells the truth, but the others are "alternate liars": they tell the truth then lie, then truth, etc, but you do not know if they will start by telling the truth or a lie...

You can ask three questions that MUST be answered by Yes or No.

Find the truth teller.

### Hint

Ask the questions to one person only.### Answer

Q1. Mr. A, are you a truth teller?- Yes

or

- No.

Q2. Mr. A, are you a truth teller?

- Yes

or

- No.

Q1: Q2:

Yes Yes: A is the truth teller.

Yes No : A is an alternate liar, next answer is a lie.

Q3: Mr. A, is B the truth teller?

- Yes: C is the truth teller.

- No: B is the truth teller.

No Yes: A is an alternate liar, next answer is true.

Q3: Mr. A, is B the truth teller?

- Yes: B is the truth teller.

- No: C is the truth teller.

No No : Impossible.

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