Crossing bridge in 15 minutes! Come on Fast!!!!
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Four people arrive at a river with a narrow bridge that can only hold two people at a time. It’s nighttime and they have one torch that has to be used when crossing the bridge. Person A can cross the bridge in one minute, B in two minutes, C in five minutes, and D in eight minutes. When two people cross the bridge together, they must move at the slower person’s pace.
Can they all get across the bridge in 15 minutes or less?
Best answer
Consider first A & B cross the bridge. A returns with the torch.
Time taken is 2 + 1 = 3 minutes
Then C & D cross the bridge. However, B returns with the torch.
Time taken is 8 + 2 = 10 minutes.
Now, both A & B cross the bridge.
Time taken is 2 minutes.
Total time taken: 3 + 10 + 2 = 15 minutes.
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