🚀 go-pugleaf

Probability puzzle
This puzzle sounds similar to the two children one discussed here 
already but I've never heard a satisfactory explanation:

You and two other people (call them B and C) are locked, in separate 
cells, in a prison.  You are told that two of you are to be executed. 
So you calculate your chances of survival to be 1 in 3.

The gaoler wanders round and you say to him that, since clearly at 
least one of the two other chaps is going to die, he wouldn't be 
giving anything away by telling you which one. He does - say B. Now, 
amazingly, you calculate your chances of survival as 1 in 2 since it 
is clear that either C or you will be the other victim.

So, you think to yourself, you fooled the gaoler. His information was 
(somehow) able to improve your chances of survival. Then you wake up 
and realise that you never had that conversation at all. However, you 
pretend that you do have this conversation. Whichever other prisoner 
he tells you is for the chop your chances are still 1 in 2. So in fact 
your chances of survival were 1 in 2 all along ...

Errrmmmm.

Richard
--

Richard Develyn from Hastings, Sussex, England ( rad@cix.compulink.co.uk ).
Software engineer (datacomms) for Cray Network Systems. Married to Caroline.
Baby daughter Sophie (b. 3/11/92). Hobbies: Dr Who, FRPG, SF, Curry,
quality computer games, philanthropic discussions.