Hard
Unsolvable Riddles
25 XP

Sleeping Beauty Problem

3,791 solved 64% solve rate 36% fail rate
Beauty is put to sleep. A coin flip determines if she wakes once or twice with memory wiped. When woken, what is P(Heads)?
Only 64% solve this correctly
3,791 attempts
Earn +25 XP for solving
Quick Answer & Explanation
1/2 or 1/3

The answer to this riddle is 1/2 or 1/3. Difficulty: Hard · Solved by 3,791 puzzle lovers.

Think carefully about the key words: 1/2 or 1/3
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