Question

Puzzle : Bridge Crossing

Jim, Jeanne, Louis and Anne wants to cross the bridge at night. They have only one torch light with them. Only two can cross the bridge at a time. They need torch light to cross the bridge. Each of them walks at a different speed. Jim needs 1 minute, Jeanne needs 2 minutes, Louis needs 5 minutes and Anne needs 10 minutes. A pair must walk together at the rate of the slower person. How these people can cross the bridge within 17 minutes?

Answer 1

First Jim and Jeanne walks across the bridge, it takes 2 minutes. 

Jim walks back with the torch light, which takes 1 minute. 

Then Louis and Anne walk on the bridge, which takes 10 minutes.

Jeanne comes back with the torch light, it takes 2 minutes.

Finally Jim and Jeanne walks across the bridge, which takes 2 minutes.

Total = 2 + 1 + 10 + 2 + 2 = 17 minutes