| Topic Name: |
Brainteaser |
| Message Name: |
Solution described |
| Date Posted: |
03/25/2002 |
| In Reply To: |
Perhaps someone can help solve this question.
3 prisoners and a jailer. A bag with 3 black and 2 red hats. The prisoners are blind folded and each selects a hat and puts it on his head. The jailer will let them go if anyone of them can identify the color of the hat on his head and explain why he knew the color. In other words they just can't guess. They can see each others hats but not their own. The jailer asks the first prisoner if he knows and he says no. Then
he asks the second prisoner and he says no. The third prisoner is blind but when he is asked he correctly identifies the color and explains how he knew it. |
| Message: |
Assuming the 3 prisoners have some ability to reason logically... based on the keywords - 2 red hats;
1. Prisoner 1 can't tell the color of his/her hat unless he/she sees the other 2 wearing red hats - in which case he/she will be wearing a black hat.
2. Prisoner 2 can't tell either for the same reason given in 1. above.
3. So then... it's obvious that P1 sees a red and a black hat in P2 and P3, AND P2 also sees a red and a black hat in P1 and P3, which now leaves Prisoner 3 to deduce that he/she must be wearing the black hat since P1 and P2 must have seen a red hat each => 2 red hats already.
Let's not go into statistical combinations yet...
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