One Question About Three Tokens An honest man has three tokens – white, gray, and black. He secretly chose one of the tokens, and allows you to ask him one question, which he can answer “Yes”, “No”, or “I don’t know” (the questions assuming other possible answers are not allowed). Can you determine which token the man chose? Dmitri Papichev Tuesday, June 14, 2005 Hmm... So the trick is to get three unique answers for the three different stones. How about: "In my closed fist I have a gray stone of my own. Is the stone you chose darker than mine?" Answer: Black: Yes White: No Gray: I don't know Hmm... the only other ones I can think of are similar shade-comparing questions. Any other class of question you can think of? BradC Wednesday, June 15, 2005 We consider gray as a distinct color, not a range of colors. So the answer in case of the gray token chosen will be "No" - the same as in case of the black token. Thus, we need some other question. Dmitri Papichev Wednesday, June 15, 2005 If I chose a stone that you did not pick, would my stone be darker than yours? black: no white: yes gray: I dont know WanFactory Wednesday, June 15, 2005 Solved! :) Dmitri Papichev Thursday, June 16, 2005   Fog Creek Home