All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Probability
The Sleeping Beauty problem (Posted on 2018-01-22) Difficulty: 3 of 5
Some researchers are going to put you to sleep.

During the two days that your sleep will last, they will briefly wake you up either once or twice, depending on the toss of a fair coin (Heads: once; Tails: twice). After each waking, they will put you to back to sleep with a drug that makes you forget that waking.

When you are first awakened, to what degree ought you believe that the outcome of the coin toss is Heads?

No Solution Yet Submitted by Jer    
No Rating

Comments: ( Back to comment list | You must be logged in to post comments.)
Just one word. Comment 4 of 4 |

When you are FIRST awakened,...

The assumption is that the narrator who is giving the information is telling the truth.  The probability is then 1/2.

Some versions of the problem avoid this conclusion by different wording, so that you don't know whether it is the first time you woke up, or just the first time you remember waking up. In that case, I agree with Charlie's analysis.

  Posted by broll on 2018-01-22 20:58:50
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (2)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (1)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2020 by Animus Pactum Consulting. All rights reserved. Privacy Information