You are given two special fuse wires, and plenty of matches. Each wire, if lit at one end, will burn for exactly 60 minutes. However the rate of burning is not regular, so cutting a fuse wire in half does not mean a burn time of 30 minutes.
You need to time 45 minutes. How do you do it?
Answer on the next page!
In order to time 45 minutes, you need simultaneously to light both ends of the first fuse, and light one end of the second fuse.
After 30 minutes, the two burning ends of fuse one will meet, and fuse two will have 30 minutes of burning time left.
Light the remaining end of fuse two. 15 minutes later, the two burning ends of fuse two will meet.
You have timed 45 minutes!