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Many heads (Posted on 2004-12-13) Difficulty: 3 of 5
What is the expected number of times you must toss a (fair) coin until you get n consecutive heads?

See The Solution Submitted by e.g.    
Rating: 4.3333 (3 votes)

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Solution Solution | Comment 5 of 6 |

Take each group of n flips. There is a 1/(2^n) probability that it is all heads. Therefore, the n heads should start on the (2^n)th flip. The last head will be the ((2^n)+n-1)th flip. Therefore, the answer is (2^n)+n-1.

  Posted by Math Man on 2011-04-24 22:27:29
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