Five Ghost Bridge Crossing Puzzle | MindYourLogic Bridge Crossing Puzzle

In the "Five Ghosts and the Lantern Puzzle," five ghosts with different crossing speeds need to cross a narrow bridge at night using a single lantern. The bridge can hold a maximum of two ghosts at a time, and the lantern must be carried back and forth by the ghosts. The challenge is to determine the minimum total time required for all five ghosts to cross the bridge, which is 25 minutes. This puzzle requires careful planning to minimize the crossing time, especially given the different speeds of the ghosts.

Conditions:

Ghost 1: 1 minute
Ghost 2: 2 minutes
Ghost 3: 5 minutes
Ghost 4: 8 minutes
Ghost 5: 12 minutes

The bridge can hold at most two ghosts at a time.
The lantern must be carried by those crossing the bridge.
Steps to Cross the Bridge in Minimum Time:

First Crossing:

Ghost 1 (1 minute) and Ghost 2 (2 minutes) cross the bridge together with the lantern.
Time taken: 2 minutes (the time of the slower ghost, Ghost 2).
Ghost 1 returns with the lantern.
Time taken: 1 minute.
Total time elapsed: 3 minutes.

Second Crossing:

Ghost 4 (8 minutes) and Ghost 5 (12 minutes) cross the bridge together with the lantern.
Time taken: 12 minutes (the time of the slower ghost, Ghost 5).
Ghost 2 returns with the lantern.
Time taken: 2 minutes.
Total time elapsed: 17 minutes.

Third Crossing:

Ghost 1 (1 minute) and Ghost 3 (5 minutes) cross the bridge together with the lantern.
Time taken: 5 minutes (the time of the slower ghost, Ghost 3).
Time taken: 1 minute.
Total time elapsed: 23 minutes.

Final Crossing:

Ghost 1 (1 minute) and Ghost 2 (2 minutes) cross the bridge together with the lantern.
Time taken: 2 minutes (the time of the slower ghost, Ghost 2).
Total time elapsed: 25 minutes.

Conclusion:

By following the outlined steps, all five ghosts can cross the bridge in a total of 25 minutes. This solution involves strategic planning to minimize the time required, particularly when managing the slower ghosts. The approach optimizes the use of the lantern and the crossing times to achieve the minimal total time, given the constraints of the problem.