130.Three Bowls
★★★conditional probabilityHudson River Trading
Three bowls each hold two balls: one has two blue, one has two red, and one has one of each. You pick a bowl at random and draw a ball from it, and it is blue. What is the probability that the other ball in that same bowl is also blue?
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Count blue balls rather than bowls. The all-blue bowl had two ways to hand you a blue ball; the mixed bowl had one.
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