Now start by lighting both ends of one rope and one end of other rope. PuzzleFry is the hub for interview puzzles, brain teasers, logic puzzles, brain games, riddles, Logical Questions, Math and Number Puzzles and quizzes. The ropes are non-homogeneous in nature. Start by creating a 2 minute rope as you described. Later, people started keeping track of the time of the day. They burn unevenly in different parts though – it means that one half can burn for 20 minutes and other half for 40 minutes. By creating an account I have read and agree to InterviewBit’s Measure Time by Burning Ropes Problem You have two ropes and a box of matches. The rope burns at the rate of one rope per hour, but it may not burn uniformly. Burning ropes to measure time. How can you measure a period of exactly 45 minutes? it compeletes its burning in 15 mins. Log in. Each rope takes exactly one hour to burn, but they don't burn at a constant rate. Warm-up: You are given a box of matches and a piece of rope. Light both ends of rope A and one end of rope B. Destroy it (burn both ends) Reduce its length by N/2 (burn one end) You need to destroy at least one rope in order to reduce the rest, because you have no other way of keeping time. and Each rope has the following property: If you light one end of the rope, it will take one hour to burn to the other end. Interview Question: The Burning Rope. Then start burning three 7 minutes rope at the same time, for 2 min. Change ), You are commenting using your Google account. They are made of different material so even though they take the same amount of time to burn, they burn at separate rates. You must start by lighting one or both of the ropes. ( Log Out /  1. When Rope 1 finishes burning, it will be … (Can be found in Leino’s puzzle page) Puzzles are usually asked to see how you go about solving a tricky problem. They don’t necessarily burn at a uniform rate. You have two ropes and a lighter. Change ), You are commenting using your Facebook account. He actually wants to measure 45 mins. Thats one hour. At this point burn the rope 2 at the remaining end and it will burn off completely in 15 mins. Two burning ropes are needed to measure 45 minutes exactly. first burn 2 sides of rope one and a single side of rope 2. so the first rope compeletes its burning in 30 mins. 2 hrs. After 30 minutes, rope A will be completely burned up and there will be 30 minutes of rope B left. The rope burns at the rate of one rope per hour, but it may not burn uniformly. Burn Rope 1 from both end and at same time burn Rope 2 from one end. How do you measure out exactly 45 minutes? You need to measure exactly 45 minutes. now burn the 2nd rope from the other side. I’ve heard a version where you get two ropes and need to time 15 min. This is because in time N/2, for one rope you can either. Change ). They started building various instruments to divide the day into smaller parts. Both of the ropes will take exactly an hour each to burn fully. The rope burns at the rate of one rope per hour, but it … an hour. This gives the learners time to apply their learning. By the time rope one burns it will be 30 mins. Each takes exactly 60 minutes to burn. 1/2 + 1/4 = 3/4 = .75 = 45 minutes. Given these two ropes and a matchbook, can you find a way to measure out exactly 45 minutes? See Figure 1. Wait… You only get one rope? Simultaneously light both ends of A and one end of B. 947.7K Views. You can subscribe via RSS 2.0 feed to this post's comments. Each of them burns for one hour. Step #3. 7 minutes hourglass is left with 3 minutes. Burning Rope Puzzle - Measure 45 Minutes. Check out my other brain teasers if you enjoy this. At 4 minutes: 4 minutes hourglass runs out and flip it. Thus, at this point B will have 30 minutes of burn time left and will be burning from both ends. Log in to your account. An […] You have two ropes. When A has completely burned, which will be 30 minutes later, light the unlit end of B and say "start". Rope 2 would also burn to a point where only 30 mins are left for it to burn completely. The rope burns at the rate of one rope per hour, but it may not burn uniformly. In addition you have a box of matches. The same applies to the measurement of business impact and financial benefits such as calculating the ROI of training. 0; ... Each rope burns in 60 minutes. Each rope is made of a different material and burns differently from the other. First rope + Second 30 mins + Second rope 15 mins = 45 mins. You are given a box of matches and a piece of rope. Two ropes are given to you. In addition, each rope burns inconsistently. Therefore, the total time to burn both ropes is 30 + 15 = 45 minutes. This entry was posted on December 15, 2007 at 9:30 pm and is filed under Puzzles. How can you do it? How can you measure a period of 45 minutes? the rule is you cannot cut the rope, you cannot extinguish the fire, and you can burn the rope from both ends. Answer: Light up … This doesn’t seem possible unless unless everytime you cut the rope you get more ropes that take an hour to burn. Then when you have half of one left, you cut that half in half, so .75 hours or 45 minutes. Solution: At 0 minutes: Start both hourglasses at the same time. For example, if you light the rope at one end, it will take exactly 60 minutes before the entire rope has burnt up, but it may be that the first 1/10 of the rope takes 50 minutes to burn and that the remaining 9/10 of the rope takes only 10 minutes to burn. A 1 hour B 30 minutes C 45 minutes D 15 minutes ( Log Out /  Top class website yours sincerely, Shaunte Shiraki. When you burn both ropes, it's 2 hours of burning, cut in half because your burning them at the same time. : Unsolved NUMRANGE : Solved NEXTGREATER : Unsolved Best Time to Buy and Sell Stock with Tr : Solved TOP VIEW : Solved Merge elements : Unsolved Fake Note : Solved Loops- Java : Unsolved Kth Permutation Sequence : Solved Random Attendance : Solved Maximum Frequency stack : Unsolved Balanced Brackets Queries : Solved Seats : Solved Diameter of Binary Tree : … 3. At 7 minutes: 4 minutes hourglass is left with 1 minute. Whats the time you can measure using the 2 ropes? and now the 2nd rope has burned 30 mins so time left for its burning is 30 mins. But either rope has different densities at different points, so there’s no guarantee of consistency in the time it takes different sections within the rope to burn. You have 2 ropes. How do you use these two ropes to measure 45 minutes? Create a free website or blog at WordPress.com. They are made of different material so even though they take the same amount of time to burn, they burn at separate rates. You are asked to measure 45 minutes by using these two ropes. To measure behavioral changes, you should wait two or three months after the training has been completed. Log In using or. Most companies avoid asking it, because most puzzles hinge on a single trick which can be easily missed by a person when he is having a bad or nervous day. However if we start burning both the ropes, they will burn at exactly same time i.e. Please note that you can’t break the rope in half as it is being clearly stated that the ropes are non-homogeneous in nature. You can choose the starting time. 4 & 5. Is it right to say"Burn 1 rope at 4 places,it burns for 15 mins"? so total 45 mins.. if u have any more doubts read the question once more How do we measure 45 minutes exactly by burning both ropes. There are two ropes, each rope takes 1 hour to burn. Call the ropes A and B. we have all seen problems regarding time measurement by burnin certain length of uneven ropes that burn at certain times. so you can measure 45 minutes. When rope B has completely burned, say "done". So the total time can be calculated like below. He can’t cut the one rope in half because the ropes are non ... he will burn the other end of the second rope so now it will take 15 mins more to completely burn. Burning ropes to measure time (Can be found in Leino’s puzzle page) You are given a box of matches and a piece of rope. How do you measure out exactly 45 minutes? for example, how do you measuer 45min with a rope that burns in 30 min and the other that burns in 60? Famous Burning Rope Measure Time Problem Mind Teasers : Famous Burning Rope Measure Time Problem Difficulty Popularity Two ropes are … Already an Interviewbit user? ( Log Out /  / 2 = 1 hour. ( Log Out /  when first rope is finished burning(in 30 minutes) then light other end of second rope ,in this way second rope half second rope is already burned so it will take more 15 minutes with both ends burning. Puzzles presented and solved at lunch break on Fridays, by SEN3, CWI. Learn Tech Skills from Scratch @ Scaler EDGE, Largest area of rectangle with permutations, Best Time to Buy and Sell Stock atmost B times, Construct Binary Tree From Inorder And Preorder, Minimum Characters required to make a String Palindromic, Convert Sorted List to Binary Search Tree, Possibility of finishing all courses given pre-requisites, First non-repeating character in a stream of characters, Numbers of length N and value less than K. Didn't receive confirmation instructions. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. A)1 hr We can measure 30 minutes by burning one rope at both ends, so we can solve this if we can measure 20 minutes on the other rope. Burning ropes to measure time (Can be found in Leino's puzzle page) You are given a box of matches and a piece of rope. You are left with three 5 min ropes. How can he measure 45 mins using only these two ropes. Measuring job impact, business impact, and ROI. Email * Password * Remember Me Privacy Policy. Measure Time by Burning Ropes: You have two ropes and a box of matches. Measurement Of Time In the beginning, people used calendars to keep a track of years, which were divided into months and days (not exactly what we use today, but something similar). Measure 15 minutes! Terms You have two ropes. 0. Mark all times you can measure by burning these two ropes. Each rope takes exactly one hour to burn, but not necessarily evenly; that is, the first half might burn in the first 10 minutes and the second half in 50 minutes. More precisely, given the matches and the rope, you are to say the words “start” and “done” exactly 45 minutes apart. I have 1 rope which burns for 1 hour(It doesnt burn uniformly.Half the rope may get burnt in 10 mins remaining in 50 mins or something like that)I need to measure 15 mins. Each rope takes exactly one hour to burn, but they may not necessarily burn evenly – i.e., the first half might burn in the first 10 minutes and the second in the remaining 50). Start burning a 16 minute ropes for three times five minutes. Total time elapsed since starting the ropes on fire: 45 minutes. How would you measure 50 minutes? You can light or extinguish either end of either rope later, but you must only do this immediately after a rope has finished burning, as this is the only accurate way to measure elapsed time. Burning of two ends of it at the same let you you measure 30 minutes. Change ), You are commenting using your Twitter account. Light the other end of rope B; it will burn up in 15 minutes. 7 minutes hourglass runs out and flip it. Burning Rope Timer Puzzle. Each rope takes exactly one hour to burn, but they may not necessarily burn evenly – i.e., the first half might burn in the first 10 minutes and the second in the remaining 50). The Rope Burning Puzzle You have two ropes and a lighter. 1/2 hour is plain and 1/2 hour is devided in half, so 1/4 hour. Note that the ropes will not burn at a consistent speed the entire time (for example, it's possible that the first 90% of a rope will burn in 1 minute, and the last 10% will take the additional 59 minutes to burn). Each takes exactly 60 minutes to burn.