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The Two Ropes Burning Puzzle

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The “Two Ropes Burning” puzzle is a classic problem that challenges your ability to measure time intervals with limited resources. Here’s how it goes:

You have two ropes of different thicknesses, and both ropes burn completely in exactly one hour. However, the ropes don’t burn evenly, meaning that half the rope might burn in 20 minutes, while the other half takes 40 minutes to burn.

Using only these two ropes and a way to light them, How to Measure Exactly 45 Minutes?

The Two Ropes Burning Puzzle

The Two Ropes Burning Puzzle Solution

Here’s one solution to the problem:

Due to inconsistent burning rates of the ropes, measuring 75 percent down one rope and assuming it is equivalent to 45 minutes is not accurate. This is because the rope may burn slower or faster in the last 25 percent. However, if both ends of one rope are lit at the same time, the rope will burn completely in 30 minutes, irrespective of the difference in burning rates between the ends.

To measure 45 minutes using two ropes, one rope is lit at both ends, and the second rope is lit at one end simultaneously. When the first rope burns out, 30 minutes have elapsed. At that moment, the unlit end of the second rope is lit. Though this does not imply that half of the rope’s length has burned, 30 minutes of the second rope have already been consumed. As a result, lighting the other end of the second rope when the first rope burns out causes the remaining part of the second rope to burn up in 15 minutes. The second rope will have completely burned in 45 minutes once the flames have consumed it.

Another way to ask the same question in an interview is “Two ropes are provided, each with different thickness, density, width, and length. Both ropes have a burn time of 60 minutes. The task is to measure precisely 45 minutes using only these two ropes. However, cutting one rope in half is not an option due to their non-homogeneous nature, which makes it difficult to determine the burn time accurately.”

Solve the classic “Two Ropes Burning Puzzle” with this step-by-step explanation. Learn how to use two non-homogeneous ropes to accurately measure 45 minutes, without cutting them in half. Perfect for testing your problem-solving skills and logical reasoning abilities.

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