Sunday, March 2, 2008

Looks like SPAM...

One million (1000000) people receive an e-mail with the following message:
  • If *exactly* one of you will reply to this e-mail, everyone of you will win 100\$. In any other case, everybody will win nothing.
Suppose that the people receiving this e-mail are all very intelligent, they are willing to win the prize, and they cannot comunicate with each other. The only thing that they can do is just replying, or not. Ah, the e-mail is not SPAM, it is serious :)

What is the best strategy that they can adopt to maximize the probability of succeding? What is (more or less) the probability of success?

Update (20/03/2008): Solution posted! (show solution)


nico said...

a very clever solution
just a joke :)

let 's suppose that any mail arrives in the same moment it is sent. if one reply to all recipient he is 'almost-sure' that no other lucky people had replied at the same moment.

Stregatto said...


BTW, i'm sure that no solution could ever work in the real world. I mean, some idiots would surely reply in any case, and you could do nothing to prevent it :)