Many years ago when a person who owed money could be thrown into jail, a merchant in London had the misfortune to owe a huge sum to a money lender. The money lender, who was old and ugly, fancied the merchant’s beautiful teenage daughter. He proposed a bargain. He said he would cancel the merchant’s debt if he could have the girl instead.
Both the merchant and his daughter were horrified at the proposal. So the cunning money lender proposed that they let Providence decide the matter. He told them that he would put a black pebble and a white pebble into an empty moneybag and then the girl would have to pick out one of the pebbles. If she chose the black pebble she would become his wife and her father’s debt would be cancelled. If she chose the white pebble she would stay with her father and the debt would still be cancelled. But if she refused to pick out a pebble her father would be thrown into jail and she would starve.
Reluctantly the merchant agreed. They were standing on a pebble strewn path in the merchant’s garden as they talked and the moneylender stooped down to pick up the two pebbles. As he picked up the pebbles the girl, sharp eyed with fright, noticed that he picked up two black pebbles and put them into the moneybag. He then asked the girl to pick out the pebble that was to decide her fate and that of her father.
Imagine that you are standing on that path in the merchant’s garden. What would you have done if you had been the unfortunate girl?
-from Lateral Thinking by Edward DeBono
Augmental 
I would pull both stones out of the bag at once and expose the merchant as a dishonorable man.
Thanks, Margaret, I didn’t think of that.
Unfortunately, this answer might not keep her father from going to jail.
How could she take advantage of the money lender’s ruse and get him to relent to the more positive outcome for the girl and father?
i would palm a white one in my hand or make arun for it
take one pebble and hide it in your hand or throw it away. then tell them to look in the bag at the pebble left in there. since the pebble in the bag is black that means she got the other pebble.
I like zeke’s idea, but I’d eliminate the risk of getting caught. As the girl, I’d ask my father to pick one stone from the bag, and explain that my choice would be the stone remaining in the bag.
Dad will pick one of the two black stones, and the creepy lender will have to choose between exposing himself as a cheat, or accepting the outcome. He loses either way, but only losing the girl and the money is preferable to losing his honor as well.
good idea steve,
here would be my idea tho:
pretend to trip and fall down and grab a white stone in a hand
keep it balled in a fist, insert the hand into the bag and pull it back out with the white stone in hand
might not worth. but worth a try at lack of other ideas
Just pick up a stone from the path, ofcoarse! I’m with Anna.
This image is of 11 year-old Ivana Baquero. She played Ofelia in the 2006 Spanish language fantasy film Pan’s Labyrinth, or in Spanish it is El laberinto del fauno.
She can drop the pebble on the ground after she takes it out (accidentally) and say that her pebble must be the opposite of the pebble in the bag.
pick a pebble, throw it away before anyone sees it, then say it was a white one. if proven wrong, ask to see which is left in the bag (since a black pebble is left over, then the one chosen and thrown away could only have been a white one !)