An old man, with four sons and three daughters, buried a safebox with valuables inside. He wanted his children to get it when he died, but neither the boys nor the girls to get it all for themselves; he desired that at least two sons and two daughters had to be involved in order to find the missing treasure.

(For example, the three girls on their own couldn't find the treasure, even if one boy helped them. The four boys and one girl couldn't find it either.)

How could he manage this?

I also found a solution that has to do with keys... but the actual, metal, ones, not the cryptographic variety.

The man put a map in a box with seven locks, numbered 1 to 7. Then, he gave:

1st boy: keys 1,2,3
2nd boy: keys 1,2,4
3rd boy: keys 1,3,4
4th boy: keys 2,3,4

1st girl: keys 5,6
2nd girl: keys 5,7
3rd girl: keys 6,7

Two boys and two girls can open the box and get the map... the only thing that bothers me is that ONE single child, with a pair of bolt cutters, could also get the treasure...

Posted by e.g. on 2005-07-17 15:16:59