Burning Rope Puzzle

Burning Rope Puzzle

You have two ropes. Each of them burns for one hour. They burn unevenly in different parts though – it means that one half can burn for 20 minutes and other half for 40 minutes. In addition you have a box of matches. Measure 15 minutes!
You have two ropes. Each of them burns for one hour. They burn unevenly in different parts though – it means that one half can burn for 20 minutes and other half for 40 minutes. In addition you have a box of matches. Measure 15 minutes!

Solution:


Step1:   Ignite both the ends of the first rope and only 1 end of the second rope. at the same time As soon as your first rope is burnt completely in 30 mins, you are left with 30 min of the other rope with one end unburnt.

Step2: Now ignite both the ends of the leftover 30 min length of rope 2, it will burn in 15 mins.

You have two ropes. Each of them burns for one hour. They burn unevenly in different parts though – it means that one half can burn for 20 minutes and other half for 40 minutes. In addition you have a box of matches. Measure 15 minutes!
You have two ropes. Each of them burns for one hour. They burn unevenly in different parts though – it means that one half can burn for 20 minutes and other half for 40 minutes. In addition you have a box of matches. Measure 15 minutes!
Rope 1: In 30 mins rope 1 will burn completely.
Now after 30 mins put fire on Rope 2 from both end which is also half burnt.
You have two ropes. Each of them burns for one hour. They burn unevenly in different parts though – it means that one half can burn for 20 minutes and other half for 40 minutes. In addition you have a box of matches. Measure 15 minutes!
After 45 mins Rope 1 will be burnt completely. And rope will also be burnt completely but now we have measured the 15 mins in which the 2nd rope has burnt.

2 comments on “Burning Rope Puzzle”


    • PIYUSH

      if i were to simplify the statement then, suppose you got a ropes which burns in total 60 minutes total (40 + 20 given). now measure 15 minutes using two such ropes.

      hope now everything is clear

      answer:
      1. rope 1 burn from both end i.e it burns in 60/2 = 30 min (till here its simple right)
      2. now the catch or say the tricky thing is…that when u start with the rope 1 also burn the rope 2 but this time only from 1 end
      3. now u are left with {1 fully burned rope and a rope which will burn fully in 30 minutes right}
      4. now u know how to find that 15 minutes…simply (burn the remaining rope equivalent to 30 minutes again from another end too)
      > resulting 30/2 = 15 minutes.