Originally Posted by Elli

I'm going to take a stab at the prisoner one, though I usually suck at these.

The inmates should decide that the first person only should flip the switch to 'on'. Then if anyone finds it in the off position after that, they know a) the warden is messing with them or b) there's a new prisoner in the mix. So after it's been switched to off, then can guess option 3?

Errr.. that doesn't even make complete sense.