248.Painting Balls Until They Match
★★★markov chainsJump Trading
A bag holds 4 balls: 2 red and 2 black. You draw two balls at random, paint the second one the colour of the first, and return both. You repeat until all four balls are the same colour. What is the expected number of operations?
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The state is just the number of red balls. Work out how it can move in a single step and set up an equation for each state.
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