Snail and Wall | Puzzles for Interview - Interview Preparation PDF Download

Introduction 

The puzzle introduces a snail that wants to reach a water shore but is faced with a hurdle of a 30 feet high wall. To reach atop the wall, the snail has a time limit of 30 hours, which starts as soon as it begins to climb the wall. The question posed is how many hours will it take for the snail to reach atop the wall, given that it slides down 2 feet every hour it climbs 3 feet.

Solution

To solve the puzzle, it is important to understand that for every hour the snail climbs 3 feet and slides down 2 feet, it only climbs 1 foot in actual height. This means that in 25 hours, the snail would have climbed 25 feet, in 26 hours it would have climbed 26 feet, and in 27 hours it would have climbed 27 feet.

Final Climb

However, things change after the snail climbs 27 feet. At this point, the snail has covered 3 feet up in 1 hour. Therefore, in the 28th hour, the snail would have climbed 30 feet up the wall and would have reached atop the wall. Hence, the answer to the puzzle is 28 hours.

Conclusion

In conclusion, the puzzle presents a scenario where the snail has a time limit of 30 hours to reach atop a 30 feet high wall. By climbing 3 feet up and sliding down 2 feet every hour, the snail only makes an actual climb of 1 foot in an hour. However, after climbing 27 feet, the snail covers 3 feet up in 1 hour, and in the 28th hour, it reaches atop the wall.