Challenge #1 – Prison Break

Can you help your friend escape? 🔒


Before you can begin the heist, you need to build a team of people you can trust. You received news that your good friend and former accomplice has almost escaped prison and is impersonating a guarding robot waiting for a chance to exit.

When you arrive at the prison gates, you notice there are 5 guards but cannot tell which is your friend. You only know one thing:

Each robot guard always lies for the whole day, or always tells the truth for the whole day (but your friend is not bound by these rules). Can you figure out which guard is your friend and help them escape?

  • Guard A: “Today, I tell the truth”
  • Guard B: “Yesterday, I lied”
  • Guard C: “Today, I lie”
  • Guard D: “Yesterday, I told the truth”
  • Guard E: “Tomorrow, I shall tell the truth”

This week we’ve spoken a lot about making assumptions that could lead to incorrect conclusions, so if you’re struggling, have a think about anything you may have assumed implicitly…

The difficulty level reflects how long we might expect for someone to spend on this vs some of our future problems. Of course, some may rate this as a 3 or 4, whereas others may rate it at a 1. How difficult you find this is very relative, but the problem does not assume any prior knowledge of maths.

The solution is revealed in the post Challenge #1 – Prison Break – Solution.