[Puzzle: Can you help 10 students get A+?]
By: DUAN Yanlin, Alan (Jockey Club Academy Hall)
Feeling sleepy and tired in this busy week? Burning night oil because of your finals preparation? How about trying out an interesting puzzle together to make your brain back to work?
10 students are taking an unusual GE course. Every day, the teacher will randomly invite one student entering into a room, in which a coin was put on the desk, initially with its head up. In the room, the student can only choose to do (or not do) two things: 1) choose to flip the coin or not; 2) claim that all 10 students have been to this room by now. If he/she is wrong, then the game is over immediately and all students will fail this course. If he/she is right, then all 10 students will get A+. Due to academic integrity, no one can talk to each other anymore once the course starts and no one can see the coin unless they are in the room. The question is: if the 10 students are allowed to come up with a strategy together before the course officially starts, what their plan would be so that all of them can finally get an A+?
Feel free to leave your thoughts and answers at the bottom of this page. It is also welcomed to share this article together with your ideas to Facebook or Weibo with tag #ResLinkBrainTeaser. We will post the solution very soon!
Happy puzzle solving!
Puzzle adapted from: http://www.cut-the-knot.org
文: 段延麟 (賽馬會群智堂)