You have two jars, 50 red marbles and 50 blue marbles. A jar will be picked at random, and then a marble will be picked from the jar. Placing all of the marbles in the jars, how can you maximize the chances of a red marble being picked? What are the exact odds of getting a red marble using your scheme?

2 Answers on this Question

1. put 1 red marble in one jar and all the rest (99) in the
   other.
   This gives you 50% from the first jar (if they pick that
   jar they will get red 100% of the time). For the other jar
   the chances are 49/99 or 49.494949%. Divide that by 2 and
   its 24.7474%. Total odds are 50% plus 24.7474% = 74.7474%

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2. So long as you have at least 1 red marble in each jar you
   have 100% chance of a red marble being picked. The question
   only states that the jar is selected at random.

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