Save the terrified astrologer!
Once upon a time there was a dictator. An Astrologer forecast something bad for him; so the dictator awarded a death penalty to the astrologer. The latter pleaded for his life , so the dictator gave him a chance to save himself and decreed as follows:"I will allow you to put two white balls and two black balls in any manner you like in two urns without disclosing it to anybody. My executioner will choose one of the urns, dip his hand in to it and take out the ball. if the ball is black, he will cut off your head. If the ball is white , your life is saved. try save yourself,if you can." what would you advice the astrologer to do, in order to give himself the maximum probability of saving his life?