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Bob and his brother (Posted on 2002-04-22) Difficulty: 3 of 5
You are to meet with two brothers. You know that one of them, named Bob, has a very important package for you. Unfortunately, you never saw Bob or his brother, and don't know who is who.

To make the matter worse, one of the brothers is a pathological liar who never tells the truth, while the other never lies. Not only do you not know which is the liar and which tells the truth, but also, you do not know wether Bob is the liar or not.

Upon meeting the brothers, you can ask one short question of either of the brothers (but not both) to establish with certainty which of the two is Bob. (It is possible to do this with a question of four to five words.)

What question would you ask?

See The Solution Submitted by levik    
Rating: 3.5000 (16 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
another solution | Comment 20 of 21 |

Question he should ask would be

If I had asked your brother who is bob whom would he have pointed to.

Actual answer is contrary to the answer you get in either case.

 


  Posted by salil on 2006-02-25 06:01:41
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