Here is a place to share and have a go at some fun puzzles.
*** - tricky
** - moderate
* - easy
Don't spoil them by giving up too early!!
What letter, apart from E or Y, can be added to the following to complete this sequence? (*)
Hint wrote:
Think about what you've already got.
Answer wrote:
The answer is F. It completes the existing line _ to make an E.
A jailer arrests four men. He orders three of the men to sit in a line. The fourth man is put behind a screen (or in a separate room). All four men are given party hats (as in diagram). The jailer explains that there are two red and two blue hats. The prisoners can see the hats in front of them but not on themselves or behind. The fourth man behind the screen can't see or be seen by any other prisoner. No communication between the men is allowed.
If any prisoner can figure out and say (out loud) to the jailer what colour hat he has on his head all four prisoners go free. If the first one fails to find the colour, it's game over - they only have one chance.
The puzzle is to find how the prisoners can escape. (**)
Hint wrote:
No communication allowed... but what about silence?
Answer wrote:
For the sake of explanation the prisoners are labelled A B and C (as in diagram). Thus B can see A (and his hat colour) and C can see A and B.
The prisoners know that there are only two hats of each colour. So if C observes that A and B have hats of the same colour, C would deduce that his own hat is the opposite colour. However, if A and B have hats of different colours, then C can say nothing. The key is that prisoner B, after allowing an appropriate interval, and knowing what C would do, can deduce that if C says nothing the hats on A and B must be different. Being able to see A's hat he can deduce his own hat colour. (The fourth prisoner is irrelevant to the puzzle: his only purpose is to wear the fourth hat).
If you solve any please feel free to say how long it took you etc. but don't post any answers or spoilers in the clear!
... and feel free to share your own favourite puzzles.
Login
Register
FAQ
Search
