A bag with two colors marble in it. If you put hand in bag Q1: what will be colour of last marble you pick out? Q2: if you know value of marbles can you tell last marble color without playing game. Description of : The two marble colour are 1.Red and 2.Black . The value of marbles is unknown . Beside bag no 1 there is also bag no2 which contains infinite black marbles. When you put hand in bag no 1 you must pick two marbles and there are also some rules for replacing marbles: 1.If you put in bag 1 and pick two Red marbles replace them by putting one Black marble in the bag no( 1) 2.If you put hand in bag 1 and pick two Black ones replace them by putting again one Black marble in bag(1) 3. If you put hand in bag and pick out one Red and one Black marble replace them now by putting one Red marble in the bag . Further details are this game ends and you also find answers to both questions I mentioned above please do play the puzzle and follow all the 3 rules while playing. The bag 2 is not of much use . It is only to ensure black marbles doesn't end