Tuesday, 1 February 2011

Story of two pebbles

A farmer owed a local rich but very ugly and old man a lot of money. And the farmer had a beautiful young daughter that the old rich man favours. The latter proposed to the farmer to waive the debt in return for the hand of the beautiful daughter. Both the farmer and daughter were shocked at the proposal.

In any case, the shrewd old man wanted to make the proposal "fairer" to the young lady. He said, I will put two pebbles into the bag and you pick one. Should you pick a black pebble, you are to marry me and I will extinguish your father's debt. If you pick the white pebble, you do not have to marry me, yet I will still extinguish your father's debt. If you picked neither, I shall have your father thrown into prison.

With that said, the old man picked two pebbles from the ground which is full of pebbles and put them in a bag. The young girl's sharp eyes caught the old man stuffing two black pebbles into the bag. What can she do? Expose the cheat? Or sacrifice herself? Or let her father go to jail?

What would you do?

This calls for lateral thinking over logical thinking (For more on lateral thinking, read Edward De Bono's books).




What the girl did was she reached into the bag and picked out one pebble. And dropped it onto the ground (full of pebbles) before anyone could see the colour of the one she picked.

"Oops. Clumsy me." announce the young girl apologetically.

"Never mind. The pebble left in the bag would prove which pebble I picked first", offered the girl, knowing very well, the other pebble left in the bag is surely black. And that way, "proves" the first pebble must have been white.

The old man did not dare to reveal he cheated in the first place and therefore had to extinguish the debt without a bride in return. This is how the young lady turned a seemingly hopeless situation to a most advantageous result, with a little bit of lateral thinking.

Moral of the story - a solution exists in every problem. Just take a moment to examine it from a few more angles.

(This interesting story extracted from a PPT circulating on the internet)


  1. If the girl can spot that the old lender picked two black pebbles, sol would the old lender have been able to see that the pebble dropped was black, not white. Thus we are back to the first possibility: Exposure of the cheating.

    Where is the lateral solution?

  2. Regardless of whether he saw her drop a black pebble, what was he going to do? Say the one you dropped was black, and then show that the remaining pebble is also black? In that case everyone knows he's cheating, in which case she wins anyway.

  3. What if the People or the rich man suggest for rematch?
    I guess this story is perfect.

  4. Ha ha nice story!!!

  5. Describe the character of the moneylender on the basis of your reading of the story.