Puzzle 54 - Bridge and torch

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Solution : Alice and Ben cross the bridge in 2 minutes. Next Alice comes back with the torch in 1 minute. Next Cindy and Don cross the bridge in 8 minutes. Now Ben goes back with the torch in 2 minutes and Ben and Alice come back in 2 minutes. 

Total time taken = 2+1+8+2+2 = 15 minutes

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