I slept late last night after 3 hours of playing Age Of Empires. I guess, as an after effect, I had a peculiar dream. I was a king in the land of Anubis, had 1000 knights at my command, and had recently won a fierce battle against the followers of Osiris. I had few war prisoners set for execution.
As a gift, Anubis had given me 1000 bottles of sacred water, directly from the source of the Nile. I had organized a grand event to honor the knights with the bottles. The event was to take place exactly after 24 hours, and Anubis himself was attending. So postponing the event was out of question.
Upon learning about the event, Osiris played a trick. He poisoned one of the bottles with a deadly poison, which had no smell or color. The poison, even in minutest amount was sure to kill a person, and once consumed, there was no antidote, not even with Anubis. And Anubis even refused to replace the bottles, saying he trusted me to take the right decision.
The poison took 10 to 20 hours to take effect. The life of any knight was too precious to throw away. Moreover, the prisoners were set for execution in the celebration, so killing them before was a loss, but could not be helped.
I was facing one of the most difficult problems a king should ever face. What was the minimum number of prisoners I could use as scapegoat to find out the poisoned bottle?