Medium
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11 XP

The Coin Probability

16,301 solved 50% solve rate 50% fail rate
You flip a coin until you get heads. What is the expected number of flips?
Only 50% solve this correctly
16,301 attempts
Earn +11 XP for solving
Quick Answer & Explanation
2 flips on average

The answer to this riddle is 2 flips on average. Difficulty: Medium · Solved by 16,301 puzzle lovers.

2 flips on average. The expected value of a geometric distribution with p=0.5 is 1/p = 2.
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