This classic was written by Dr Charles Dodgson, aka Lewis Carroll, author of the Alice books.

A captive queen and her son and daughter were shut up in the top room of a very high tower. Outside their window was a pulley with a rope around it, and a basket fastened to each end of the rope of equal weight. They managed to escape with the help of this and a weight they found in the room, quite safely. It would have been dangerous for any of them to come down if they weighed 15 lbs more than the content of the other basket, for they would do so too quick, and they also managed not to weigh less either.

The one basket coming down would naturally of course draw the other basket up.

The queen weighed 195 lbs, daughter 105, son 90, and the weight 75 lbs.

How did they all escape safely?

(In reply to Solution by Jim Lyon)

"7. Send the the son and daughter up while the queen goes down."

I'm not sure that the baskets with equal weight would change their positions in terms of going up or down....

I've come to the same solution as Cheradenine apparently, which is as follows (in a bit more elaborate way than Cheradenine :-))

1. 0 up , 75 down
2. 90 down , 75 up (90 steps out)
3. 0 up, 75 down (75 taken out by 90)
4. 105 down , 90 up (90 steps into the tower)
5. 105+75 up , 195 down (105 steps back into the tower, 195 steps out and stays)
6. 75 down , 0 up
7. 75 up , 90 down (75 taken out by 105)
8. 105 down , 90 up (90 steps back into the tower, 105 steps out and stays)
9. 0 up , 75 down
10. 90 down , 75 up (90 steps out and stays)
11. 0 up , 75 down

Posted by lucky on 2002-09-19 08:56:54