431.Turning the Basket Blue
★★★expected valueCh. 6 — Random Variables and Expectation444+ Problems in Probability
A basket holds 2 red and 1 blue orbs. Each turn you draw an orb uniformly at random and replace it with a blue orb (whatever its color). Find the expected number of draws until the basket contains only blue orbs.
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Track the number of red orbs; each stage is a geometric wait.
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