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Puzzle A. Puzzle B. How many squares are there here?. You walk up to a black jar containing fewer than 20 marbles. If you reach into the jar and randomly remove two marbles out of the jar without replacing the marbles, you have a 50% chance of getting two green marbles.
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Puzzle A Puzzle B
You walk up to a black jar containing fewer than 20 marbles. If you reach into the jar and randomly remove two marbles out of the jar without replacing the marbles, you have a 50% chance of getting two green marbles. How many green marbles are in the jar before you select the two marbles?