Problem solving story: The black and white pebble dilemma

Many years ago in a small Indian village, a farmer had the misfortune of owing a large sum of money to a village moneylender. The moneylender, who was old and ugly, fancied the farmer’s beautiful daughter. So he proposed a bargain. He said he would forgo the farmer’s debt if he could marry his daughter.

Both the farmer and his daughter were horrified by the proposal. So the cunning money-lender suggested that they let fate decide the matter. He told them that he would put a black pebble and a white pebble into an empty money bag. Then the girl would have to pick one pebble from the bag.

If she picked the black pebble, she would become his wife and her father’s debt would be forgiven. If she picked the white pebble she need not marry him and her father’s debt would still be forgiven. But if she refused to pick a pebble, her father would be thrown into jail.

They were standing on a pebble-strewn path in the farmer’s field. As they talked, the moneylender bent over to pick up two pebbles. As he picked them up, the sharp-eyed girl noticed that he had picked up two black pebbles and put them into the bag. He then asked the girl to pick a pebble from the bag.

The girl put her hand into the moneybag and drew out a pebble. Without looking at it, she fumbled and let it fall onto…