Crossing a bridge at night with just one flashlight seems like a speed problem. Maybe it's not entirely.
The bridge and the lantern
Riddle statement
Four people must cross a bridge at night. They only have one flashlight, and no one can cross without it. A maximum of two people can cross at a time. Each person takes a different time to cross:
- 1 minute
- 2 minutes
- 5 minutes
- 10 minutes
When two cross together, they take as long as the slowest one takes.
What is the shortest total time in which all four can cross?