While solving this puzzle its necessary to read every word with the highest precaution. It’s possible to uncover the solution either by precise analytic thinking or just using common sense.
Clown and the King
Once upon a time there was a kingdom. A king and a clown lived in this kingdom. Unfortunately they hated each other so they agreed that they will poison each other one day.
There are only twelve vials of poison in whole kingdom and they are locked in one chamber in the castle.
The poisons have numbers from 1 to 12. The higher the number the stronger the poison. Effect on human body is simple – you drink the poison, you die. Each stronger poison neutralizes all weaker poisons which means that poison 12 neutralizes all poisons, number 11 all poisons but 12 etc. (If you drink 11 and than 12 nothing happens. If you drink 12 and than 11 you die.)
The king enters the chamber with poisons first and takes all the even poisons (2, 4, 6, 8, 10, 12). Than the clown enters and takes the rest. They meet in the throne hall where each fills one cup and hands it over to the other who immediately drinks it. Now each fills the cup once again, now for himself, and drinks it (hoping to save his own life).
What did the clown do that he woke up the second morning and the king was dead?
Premises: Each of them (the king and the clown) PRIMARILY wants to survive. If he survives he wants to poison the other as surely as possible. There is one dose of each poison – it’s not possible to divide it. The poisons are fluids without color or smell and they have the same consistency as water.
Hint
Most important thing for the king is to live. How can he make sure he survives whatever poison clown gives him?
The clown has a disadvantage - the king has the strongest poison. Though he knows that the king mainly wants to survive so he can expect which poison will be in the cup he hands him. What will he hand the king and what will he keep so that king dies but he does not?
After a couple unsuccessful combinations you will figure out what cunning clown did to the stupid king.
Answer
The king keeps poison 12 so that he can neutralize any POISON clown gives him. He pours poison 10 to clowns cup (his second strongest poison). Clown is counting on this so he has to keep poison 11 for himself to neutralize poison 10. That’s how he survives. He also knows that the king, after drinking the cup he gave him, will drink poison 12 (the reason is mentioned above). So he pours plain water into the cup for the king – he drinks water (water is not poison) and right after that he drinks the strongest poison possible (12) and dies.