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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: ( You must be logged in to post comments.)
  Subject Author Date
Some ThoughtssolutionMinerva2007-01-28 14:57:41
another solutionsalil2006-02-25 06:01:41
Thoughtssalil2006-02-25 05:55:49
re: If Bob is the liarKen Haley2004-09-22 00:01:19
If Bob is the liarRyan2004-05-03 12:45:19
No SubjectPieater2004-03-05 12:05:19
re: *just read the solution*JennaBanenna2003-10-29 00:51:29
Question*just read the solution*JennaBanenna2003-10-29 00:48:02
re: solutionSam2003-09-22 00:34:38
solutionDaniel2003-08-12 05:37:18
OH!zineera2003-05-26 14:10:43
A long pondered questionCara2003-05-08 10:30:11
3 word questionKen2002-09-11 20:26:22
re: the answerlevik2002-08-27 03:47:57
the answerKristina2002-08-26 12:41:58
re: (After reading the solution)TomM2002-08-04 03:47:29
Question(After reading the solution)Hazirah2002-08-03 23:26:31
Ai... yaah!Hazirah2002-08-03 23:19:39
try this tooCarey2002-05-28 00:18:37
no genius necessaryMike2002-05-10 15:48:19
SolutionMax Proskoff2002-04-23 12:00:19
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