Logical Puzzle - 18 Dec 2006

Solution to December’s Puzzle: Arranging Soldiers in a Row

After some soldiers misbehave, their commander decides to teach them alesson while testing their powers of logic. He blindfolds them and places hatson their heads. Some hats have a circle on them, and others have a square. Hethen arranges the soldiers in a column in front of a door and gives them thefollowing orders:

Assuming you’re one of the soldiers, here’s the logic you would follow afteryou remove your blindfold and look at the 0, 1, or more soldiers standing in therow in front of you:

January’s Puzzle: Crossing the Tunnel

Four people—let’s call them persons A, B, C, and D—need to cross a dark tunnel.Only two people at a time can cross the tunnel, and because the tunnel is verydark, a flashlight is mandatory. Person A can cross the tunnel in 1 minute, personB can cross in 2 minutes, person C can cross in 4 minutes, and person D canmake it in 5 minutes. The group has one flashlight, containing batteries that lastonly 12 minutes. What strategy will enable all members of the group to cross tothe other side in 12 minutes before the flashlight’s batteries run down?