Can you save your life Puzzle?


You are a prisoner sentenced to death.
The Emperor offers you a last chance to live by playing a simple game.

He gives you 50 black marbles, 50 white marbles and 2 empty bowls.
He then says, “Divide these 100 marbles into these 2 bowls. You can divide them any way you like as long as you use all the marbles. Then I will blindfold you and mix the bowls around. You then can choose one bowl and remove ONE marble. If the marble is WHITE you will live, but if the marble is BLACK  you will die.”

How do you divide the marbles up so that you have the greatest probability of saving your life that is choosing a WHITE marble?


SherlockHolmes Expert Asked on 22nd October 2015 in No Category.

  • 1 Answer(s)
    Best answer


    Say we put all the red marbles into JAR A and all the blue ones into JAR B. then our chances for picking a red one are:

    1/2 chance we pick JAR A * 50/50 chance we pick a red marble
    1/2 chance we pick JAR B * 0/50 chance we pick a red marble

    You would try different combinations, such as 25 of each colored marble in a jar or putting all red marbles in one jar and all the blue in the other. You would still end up with a chance of 50%.

    What if you put a single red marble in one jar and the rest of the marbles in the other jar? This way, you are guaranteed at least a 50% chance of getting a red marble (since one marble picked at random, doesn’t leave any room for choice). Now that you have 49 red marbles left in the other jar, you have a nearly even chance of picking a red marble (49 out of 99).

    So the maximum probability will be :
    jar A : (1/2)*1 = 1/2 (selecting the jar A = 1/2, red marble from jar A = 1/1)
    jar B : (1/2)*(49/99) = 0 (selecting the jar B = 1/2, red marble from jar B = 49/99)
    Total probability = 74/99 (~3/4)

    SherlockHolmes Expert Answered on 23rd October 2015.
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