In the puzzle Four people on a Bridge we met four people who needed to cross a bridge at night. In this puzzle, there are five people who must cross two sequential bridges at night. As in the original puzzle, there are some hindrances:

The bridges can only support two people crossing at a time.

Each person has a different speed in which they can cross: 10 minutes, 7 minutes, 5 minutes, 2 minutes, and 1 minute.

They have only two flashlights to share among them.

What is the shortest amount of time it will take for all five people to cross both bridges?

I think that if you have the person who takes 10 min walk across one bridge with the person who takes 7 min that in the 7 min it takes the other one will still have two min left to walk so have the person who takes 2 min walk across when the 7 min person gets off then they will have crossed at the same time and on the other bridge the person who takes 5 min an the person who takes 1 min should start crossing so within the 5 min it takes for the 5 min person to walk across the other 2 people (7min an 10 min people) will still be walking so it should only take 10 min for each person to be across the bridges.

Posted by Awdreye on 2005-06-28 07:20:57