The Perilous Rope Bridge Dilemma
I hope you’re enjoying the course. With two days left, I’ve rounded up two more great puzzles that will keep our brains sharp all the way to the end.
Here’s today’s dilemma: Four people are being pursued by a bear, and in order to escape, they need to cross a rope bridge. The bear can cross the bridge, but when they get to the other end, they will cut it loose.
The bridge is strong enough to support only 2 people at a time. The first person takes 1 minute to cross the bridge. The second person takes 2 minutes. The third takes 5 minutes. The fourth takes 10 minutes. The bear will take 17 ½ minutes to arrive.
They have a flashlight. It has battery left for only 17 minutes—and the bridge cannot be crossed without light. If they cross 2 at a time, they must always proceed so that the light is shining ahead of them.
How will they survive?
Work it out on your own first, then click the button below to find out if you’re right.
Share with friends