Q:
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
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
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