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MediumProbabilityAcceptance 41%
Roll Until All Six Faces
GoogleTwo Sigma
You roll a fair six-sided die repeatedly. What is the expected number of rolls until you have seen all six faces?
Approach
Sum the expected waits for each new face.
Waiting for the k-th new face is geometric.
Answer
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The answer is 14.7. Sign in free for the full worked solution and to check your own answer.
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