** Puzzle:** Raghav is trapped on top of a building and wishes to reach the ground safely. He has with him a piece of rope running to 150 meters of length, a sharp knife. The building is 200 meters high from the ground. Raghav notices two hooks is placed on the side of the building, one at a distance of 200 meters and another at a distance of 100 meters from the ground. Devise a plan for Raghav

to reach the ground safely using the 150 meters rope, a knife and 2 hooks.

** Solution:** Let’s try to analyze the puzzle using reverse engineering mechanism. Let’s understand this step by step and divide the building into two parts by locating 3 points as A, B and C.

- As we know that the second hook is located midway between the building, therefore for Raghav to reach 100 meters below the ground from B to C, he would definitely need a 100 meters rope. Therefore, Raghav needs to cut the 150 meters long rope into two parts using the knife he has. Raghav now has two ropes of 100 meters and 50 meters.
- Now to reach the midway of the building from A to B, he needs to come down 100 meters, but he cannot use the 100 meters rope which he needs to get down from B to C. What Raghav can do is tie one end of 50 meters rope at A and make a knot on the other side. He can fold the 100 meters rope and make it pass from the knot making a loop, thus covering the next 50 meters of length.

- On reaching B, Raghav can pull the 100 meters rope and tie one end at B and rope down to point C or the ground. Thus he can reach the ground safely.