How many Numbers of Prisoners does he need ?

A king is hosting a party and has got an information that
one out of the four bottles of wine contains poison.
He has four prisoners to be hanged next day.
But he wants to try with minimum number of prisoners.
How many numbers of prisoners does he need to find the exact poisonous bottle?

Click here for Answer

The king can try with 2 prisoners.

Let us name them prisoners A & B. A consumes a drop from Bottle 1 and B consumes a drop from Bottle 2 and both consume each drop from Bottle3.

If A dies, it means poison in Bottle 1,
if B dies Bottle 2 is poisonous,
if both die it means Bottle 3 is poisonous and
if none dies Bottle 4 contains poison