Twins

Logic Level 1

Peter and Paul are twin brothers. One of them always lies (we don't know which). The other one always tells the truth. I ask one of them: "Is Paul the one that lies?" "Yes." he answers. Did I speak to Paul or Peter?

Paul Cannot be answered Peter

View wiki
Panchajanya Das by Panchajanya Das , 19, India

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

3 solutions

Panchajanya Das
Apr 8, 2015

I spoke to Peter. If a person always lies or alternately, always tells the truth, he cannot admit he is lying (if this person were a liar, he would be telling the truth and if this person were honest, he would be lying). Therefore Paul couldn't have answered my question. Peter could answer about Paul without contradicting himself. What we don't know is who the liar is.

5 Helpful 0 Interesting 0 Brilliant 1 Confused
Ahmed Mouloudi
Apr 16, 2015

To simplify the logical possibilities starting from the statement that "Paul is a Liar" We have this :

Now both ending lead us to Peter as our "Person Of Interest".

2 Helpful 0 Interesting 0 Brilliant 0 Confused

If I was speaking with Paul then him answering "yes" would a contradiction ; so it's Peter

1 Helpful 0 Interesting 0 Brilliant 0 Confused

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...