[chuddo]

this is decent somewhat classic riddle that happens to be one of my favorites.

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There are 4 people who need to cross a narrow bridge at night with only one torch.

The four people each have different travelling times:

Person 1 crosses in 1 minute
Person 2 crosses in 2 minutes
Person 1 crosses in 5 minutes
Person 1 crosses in 10 minutes

Only two people can cross at a time and one person has to come back over the bridge to give the torch to the others still waiting to cross.

While crossing, you have to use the slowest time of the two people because they have to walk the same pace.

You have to add the person who comes back to your total time.

They need to cross in 17 minutes. How?