TED-Ed Video Lesson Transcript:
You’re on the trail of a werewolf that’s been terrorizing your town. After months of detective work, you’ve narrowed your suspects to one of five people: the mayor, the tailor, the baker, the grocer, or the carpenter.
You’ve invited them to dinner with a simple plan: you’ll slip a square of a rare werewolf antidote into each of their dinners.
Unfortunately, your pet goat just ate four of the squares, and you only have one left. Luckily, the remaining square is 50 grams, and the minimum effective dose is 10 grams.
If you can precisely divide the square into fifths you’ll have just enough antidote for everyone You’ll have to use a laser-cutting tool to cut up the square; every other means available to you isn’t precise enough.
There are 8 points that can act as starting or ending points for each cut. To use the device, you’ll have to input pairs of points that tell the laser where to begin and end each cut, and then the laser executes all the cuts simultaneously.
It’s okay to cut the square into as many pieces as you want, as long as you can group them into 10 gram portions.
But you can’t fold the square or alter it otherwise, and you only get one shot at using the laser cutter.
The full moon is rising, and in a moment someone will transform and tear you all apart unless you can cure them first.
How can you divide the antidote into perfect fifths, cure the secret werewolf, and save everyone?
Pause the video now if you want to figure it out for yourself. Answer in 3. Answer in 2. Answer in 1.
When it comes to puzzles that involve cutting and rearranging, it’s often helpful to actually take a piece of paper and try cutting it up to see what you can get.
If we cut BF and DH we’d get fourths, but we need fifths.