Color switches in a draw
An urn has 20 balls, 8 red and 12 blue. You draw 5 without replacement and lay them out in the order drawn. What is the expected number of color changes - positions where a ball's color differs from the one immediately before it (so among the 4 adjacent pairs)? Give a decimal to four places.
Show hints (2)+
- Put an indicator on each of the 4 adjacent pairs; sum by linearity.
- One adjacent pair is bichromatic with probability .
Answer
Reveal answer →Final answer
2.0211 (± 0.001)
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