This problem looks easy but needs some brain storming if you are listening it first time.
This is a logical puzzle and does not requires any maths or pen and paper.
A man has two heterogeneous ropes (that is, those two ropes are not identical, they aren’t the same density nor the same length nor the same width or thickness ). Each rope burns in 60 minutes.
He wants to measure 45 mins. So, the problem is that how can he measure 45 mins using only these two ropes.
Hint: He can’t cut the one rope in half because the ropes are non-homogeneous and he can’t be sure how long it will burn.
Please take some time before jumping on the solution.
He will burn one of the rope at both the ends and the second rope at one end. After half an hour, the first one burns completely and at this point of time, he will burn the other end of the second rope so now it will take 15 mins more to completely burn. so total time is 30+15 i.e. 45mins.
- Fold a rope in half
- Light one end
- When fire reaches fold, light other end
- Fires will meet at 3/4 length of rope or 45min