13 questions linked to/from Burning ropes as timers
229 views

### Two Fuses Burn for 45 Minutes [duplicate]

You have two pieces of delay fuse. One burns for 1 hour and the other burns for 30 minutes. Without a watch, clock, or timepiece at all... can you beyond any shadow of a doubt tell me when 45 minutes ...
180 views

### Safety Fuses and Matches [duplicate]

You have 2 safety fuses and 4 matches. Each fuse takes exactly one hour to burn, but they are not perfect so may not necessarily burn evenly from both sides. For example, the first half might burn in ...
247 views

### How can I solve my meditation problem? [duplicate]

I have been given a guide on how to reach satisfaction, and part of this guide requires me to meditate exactly for 90 minutes. I have only been provided 2 oil-soaked ropes which last for 2 hours each ...
285 views

### Two ropes and 45 mins [duplicate]

You have got two ropes of same mass, same material, same thickness and same length but mass is not uniformly distributed over the length. Both of the ropes burn in 1 hour but you cannot cut them in ...
181 views

### I need to measure exactly half an hour [duplicate]

I only have two candles, each candle burns for exactly one hour. I do not know the length of the candle. Guessing and estimation is not allowed. You are not allowed any other materials other than the ...
213 views

### Burning two fuses of variable length [duplicate]

This is an alteration (not a duplicate) of either the "Two Fuses burn for 45 minutes" or Burning ropes as timers questions. The fuses in my question are not identical and the answer(s) to the other ...
47k views

### Candle timing measurement [duplicate]

You are given two candles of equal size, which can burn 1 hour each. You have to measure 90 minutes with these candles. (There is no scale or clock). You are also given a lighter.
1k views

### Three ropes and a lighter puzzle

You are given three ropes and a lighter. The time required to burn through rope $1$ with a single flame is $20$ minutes. The time required to burn through rope $2$ with a single flame is $30$ minutes. ...
1k views

### How to rephrase this puzzle about a meditating monk and incense

Here's a math-flavored puzzle I found on Andrej Cherkaev's website that I like to give to my undergraduate math students. I've paraphrased it to try to make it clearer: A monk was instructed by his ...
3k views

### Burning ropes as timers - How many time intervals can be measured?

Note: This is a follow-up question to Burning ropes as timers. The following question and its answers may contain spoilers. To sum up the puzzle, these are the rules (slightly modified): You have ...
568 views

### Two burning ropes measure 5 minutes

Today I was at a job interview and the last question was, "How can I measure 5 minutes by lighting two ropes that each take an hour to burn but do not burn uniformly?" (classical). I know how to ...