Puzzler

Grab Your Pencil and Paper for This One!

Four people arrive at a river with a narrow bridge that can only hold two people at a time. It's nighttime and they have one torch that has to be used when crossing the bridge.

Person A can cross the bridge in one minute, B in two minutes, C in five minutes and D in eight minutes. When two people cross the bridge together, they must move at the slower person's pace.

Can they all get across the bridge in 15 minutes or less?

Solution

Yes, the group can cross in exactly 15 minutes. They must follow these steps.

1. First, A and B cross the bridge and A brings the light back. This takes 3 minutes.
2. Next, C and D cross, and B brings the light back. This takes another 10 minutes.
3. Finally, A and B cross again. This takes another 2 minutes.

Did you get it? Not many people do.